Private developer tools that run in your browser

Format JSON, convert PDFs, decode JWTs, optimize images, generate hashes, test regex and more — privacy-first tools built for everyday developer workflows.

ArrayKit is a privacy-first developer toolbox for JSON formatting, PDF tools, API utilities, encoding/decoding, security checks, regex testing, and browser-based file processing.

Popular tools

• JSON Formatter — Beautify, minify and validate JSON with error locations.
• JSON Viewer — Text + collapsible tree viewer with expand/collapse and node paths.
• JSON to TypeScript — Generate TypeScript interfaces from a JSON sample.
• JWT Decoder — Decode JWT header & payload and inspect exp / iat (no verification).
• Base64 Encode / Decode — UTF-8 safe Base64 encoding and decoding.
• Text Diff — Compare two texts line-by-line and see additions and removals.
• Merge PDFs — Combine multiple PDFs into one, with reordering.
• Image Optimizer — Re-encode and shrink images (JPEG/WebP/PNG), optionally resizing.
• Regex Tester — Test regular expressions live with matches, groups and flags.
• SQL Formatter — Format SQL for MySQL, PostgreSQL, SQL Server, SQLite, BigQuery and Oracle.
• cURL to Fetch — Convert a curl command to a JavaScript fetch() call.
• URL Parser — Break a URL into its parts and list query parameters.

Your data stays on your device

ArrayKit is built for fast, privacy-first developer workflows. Format, convert, debug, validate and generate directly in your browser — sensitive content never has to be uploaded to a server.

Browser-based processing

Every tool runs locally in your browser, so the data you work with stays on your device.

Developer-friendly workflows

Built for daily tasks: formatting JSON, debugging APIs, converting files, validating data and generating secure values.

Fast access

Open a tool and start working immediately. Account features are planned for saved tools, preferences, history and team workflows.

All tools by category

JSON

• JSON Formatter — Beautify, minify and validate JSON with error locations.
• JSON Tree Viewer — Explore JSON as a collapsible, typed tree.
• JSON Viewer — Text + collapsible tree viewer with expand/collapse and node paths.
• JSON to TypeScript — Generate TypeScript interfaces from a JSON sample.
• JSON to CSV — Convert an array of flat JSON objects to CSV.
• JSON Escape / Unescape — Escape text into a JSON string or unescape a JSON string back to raw text.
• JSON to Code — Generate Go, Rust, Python, Java, Kotlin, C# and TypeScript types from JSON.
• JSON Diff — Compare two JSON documents and see a structural, key-order-independent diff.
• JSON Schema Generator & Validator — Generate a JSON Schema from a sample or validate JSON against a schema.
• JSON Flatten / Unflatten — Flatten nested JSON to dot-notation keys, or unflatten it back.
• JSON to Zod — Generate a Zod schema (TypeScript) from a JSON sample.
• JSON to Pydantic — Generate Pydantic v2 model classes from a JSON sample.
• JSONPath Evaluator — Query JSON with a JSONPath expression and see matched values and paths live.
• JSON to TOON — Convert JSON to TOON (Token-Oriented Object Notation) and back, with an LLM token savings estimate.
• jq Playground — Run jq filters against JSON in your browser — map, select, group_by and more, with the real jq engine.
• TypeScript to Mock JSON — Generate realistic mock JSON from a TypeScript interface or type.
• JSON Schema Sample Data Generator — Generate realistic sample JSON that conforms to a JSON Schema.
• JSON to XML Converter — Convert JSON to XML and XML back to JSON, in your browser.
• NDJSON to JSON — Convert NDJSON / JSON Lines to a JSON array and back, line by line.
• Sort JSON Keys — Recursively sort JSON object keys alphabetically, with pretty-print and reverse options.
• CSV to JSON — Convert CSV or TSV to JSON with type inference and nested keys, in your browser.
• Excel to JSON — Convert an .xlsx or .xls spreadsheet to JSON, with sheet and header options, in your browser.
• Excel to CSV — Convert an .xlsx or .xls spreadsheet to clean CSV or TSV, in your browser.
• CSV to SQL — Convert CSV to SQL INSERT and CREATE TABLE statements for MySQL, PostgreSQL and SQLite.
• HTML Table to JSON — Extract HTML tables into JSON or CSV, honoring headers and colspan, in your browser.
• JSON Patch Generator — Generate an RFC 6902 JSON Patch between two JSON documents and apply a patch to a source.
• JSON Repair — Fix broken or LLM-generated JSON: trailing commas, single quotes, unquoted keys and comments.
• JSON to GraphQL Schema — Generate GraphQL SDL types from a JSON sample, inferring fields and nested types.
• JSON to SQL — Turn a JSON array into CREATE TABLE and batched INSERTs with inferred column types.

Code Formatters

• YAML ↔ JSON — Convert YAML to JSON and back.
• Markdown Preview — Render Markdown to HTML with a live preview.
• Regex Tester — Test regular expressions live with matches, groups and flags.
• CSS Color Converter — Convert between HEX, RGB and HSL with a live swatch.
• Text Diff — Compare two texts line-by-line and see additions and removals.
• MDX Converter — Render MDX as formatted text, convert HTML → MDX, and escape text to literal MDX.
• CSS / SCSS Formatter — Beautify or minify CSS/SCSS/LESS, sort properties and remove duplicates.
• JS / TS Formatter — Beautify or minify JavaScript, TypeScript and JSX/TSX with Prettier options.
• HTML Formatter — Beautify or minify HTML, format inline CSS/JS, and preview the result.
• XML Formatter — Beautify, minify and validate XML, and convert XML ↔ JSON.
• SQL Formatter — Format SQL for MySQL, PostgreSQL, SQL Server, SQLite, BigQuery and Oracle.
• GraphQL Formatter — Format or minify GraphQL queries and schemas, validate syntax and extract operations.
• Dockerfile Formatter — Format a Dockerfile and get best-practice / lint suggestions.
• MongoDB Query Formatter — Format MongoDB shell queries and aggregation pipelines.
• Contrast Checker — Check WCAG colour contrast ratio and AA/AAA pass for any two colours.
• Mermaid Diagram Renderer — Render Mermaid diagrams (flowcharts, sequence, gantt) to SVG in your browser.
• SVG Optimizer — Minify SVG — strip comments, metadata and editor cruft, and collapse whitespace.
• MongoDB Query Beautifier — Beautify and indent MongoDB queries and find() statements in your browser.
• MongoDB Aggregation Beautifier — Beautify and indent MongoDB aggregation pipelines in your browser.
• MongoDB Explorer — Explore a MongoDB document or collection sample and infer its field schema and types.
• OpenAPI / Swagger Formatter — Format and validate OpenAPI / Swagger specs (JSON or YAML) and count paths and operations.
• CSS Unit Converter — Convert between px, rem, em, pt and % live with a configurable root font size.
• Glob to Regex — Convert a glob or wildcard pattern into an equivalent JavaScript regex.
• HTML to Markdown — Paste HTML and convert it to clean Markdown live, with GFM tables, lists and code blocks.
• TOML Formatter & Converter — Format and validate TOML, and convert TOML ↔ JSON.
• logfmt to JSON — Convert logfmt key=value logs to JSON and back.
• dotenv to JSON — Convert a .env file to JSON and JSON back to .env, with quoting and comments handled.
• CSV to Markdown Table — Convert CSV or TSV data into a Markdown table, with alignment and header options.
• INI to JSON — Convert INI config files to JSON and JSON back to INI, with sections and comments.
• Markdown Table Generator — Build a table in an editable grid and export Markdown, HTML, AsciiDoc and LaTeX.
• Data Size Converter — Convert between bits, bytes, KB, MB, GB and KiB, MiB, GiB, with decimal and binary units.
• Java Properties ↔ JSON — Convert Java .properties files to JSON and JSON back to .properties, in your browser.

Text

• Case Converter — Convert text between camelCase, snake_case, kebab-case, PascalCase and more.
• Lorem Ipsum Generator — Generate placeholder lorem ipsum paragraphs, sentences or words.
• Mock Data Generator — Generate fake JSON data — names, emails, UUIDs, dates and more.
• Word & Character Counter — Count words, characters, sentences, lines, bytes and approximate tokens, live.
• Slug Generator — Turn a title into a clean, URL-safe slug, with batch mode.
• LinkedIn Text Formatter — Add bold, italic, underline and more to LinkedIn posts using Unicode you can paste anywhere.
• AI Text Cleaner — Detect and remove invisible characters and typography artifacts left by AI models and copy-paste.
• Remove Duplicate Lines — Remove duplicate lines from a list, with case, trim, keep-first-or-last and sort options.
• Fake VAT Number Generator — Generate format-valid, check-digit-correct fake VAT numbers for testing invoices and checkout forms.
• Sort Text Lines — Sort lines alphabetically, numerically, by length or randomly, with reverse, case and dedupe options.
• Find and Replace Text — Find and replace text with plain or regex search, case sensitivity, whole-word and global options.
• NATO Phonetic Alphabet — Convert text to the NATO phonetic alphabet (Alfa, Bravo, Charlie) and spell it back.
• Delimiter Converter — Convert a list of lines to a comma, tab or custom delimited list and back, with quoting.
• Fancy Text Generator — Turn plain text into bold, italic, script and other Unicode font styles you can copy.
• Remove Line Breaks — Remove or replace line breaks and join paragraphs, with options to keep blank lines.
• Title Case Converter — Capitalize titles correctly with AP, Chicago, APA and MLA style rules, in your browser.
• Readability Score Checker — Score text with Flesch-Kincaid, Gunning Fog, SMOG and more, with word and syllable stats.
• Number to Words Converter — Convert numbers and currency amounts into written words, with cardinal and ordinal forms.
• AI Text Summarizer — Summarize long text into a short summary — the AI model runs in your browser, nothing is uploaded.
• AI Sentiment Analyzer — Detect the tone of text as positive or negative with a confidence score — runs in your browser.
• AI Entity & PII Extractor — Extract names, organizations, locations, emails, phone numbers and IPs from text — runs in your browser.
• Local AI Chat — Chat with an AI assistant that runs entirely in your browser on your own device. Your conversation is never uploaded.
• Reverse Text — Reverse text by character, word or line, with Unicode-safe grapheme handling.
• Character Frequency Counter — Count how often each character or word appears in text, sorted by frequency.
• Upside Down Text Generator — Flip text upside down using Unicode look-alikes you can paste anywhere.

Encode / Decode

• Base64 Encode / Decode — UTF-8 safe Base64 encoding and decoding.
• URL Encode / Decode — Encode and decode URL components.
• HTML Escape / Unescape — Escape and unescape HTML special characters and entities.
• Number Base Converter — Convert integers between binary, octal, decimal and hex.
• QR Code Generator — Generate a QR code from text or a URL; download as PNG or SVG.
• Mojibake / Encoding Fixer — Fix garbled "mojibake" text from an encoding mismatch — turn Café back into Café.
• Protobuf Decoder — Decode a Protocol Buffers binary message (hex or base64) without a .proto schema.
• Base32 Encoder / Decoder — Encode text to Base32 and decode Base32 back to text (RFC 4648), in your browser.
• Morse Code Translator — Translate text to Morse code and Morse code back to text, with audio playback.
• Text to Binary Converter — Convert text to binary, and binary, hex or decimal back to text, in your browser.
• Base58 Encoder / Decoder — Encode and decode Base58 (Bitcoin / IPFS alphabet), with hex and text input.
• ULID Generator — Generate sortable ULIDs and decode a ULID to its timestamp, in your browser.
• Snowflake ID Generator — Generate and decode Twitter and Discord style Snowflake IDs, with timestamp extraction.
• Caesar Cipher / ROT13 — Encode and decode Caesar, ROT13, ROT47 and Atbash ciphers, with a brute-force cracker.
• Roman Numeral Converter — Convert numbers to Roman numerals and Roman numerals back to numbers, both ways.
• Bitwise Calculator — Apply AND, OR, XOR, NOT and bit shifts to integers, with binary, hex and decimal views.
• IEEE 754 Converter — Convert decimals to and from 32-bit and 64-bit IEEE 754 floating-point, with the bit fields.
• Punycode Converter — Convert internationalized domain names between Unicode and ASCII Punycode (xn--), both ways.
• Quoted-Printable Encoder / Decoder — Encode and decode Quoted-Printable (MIME =XX) text, in your browser.
• Ascii85 / Base85 Encoder / Decoder — Encode and decode Ascii85 and Z85 Base85, in your browser.
• Unicode Escape / Unescape — Escape text to Unicode escape sequences and unescape them back.
• Hex Dump Viewer — View text or a file as a classic hex + ASCII dump, with adjustable width.
• Nano ID Generator — Generate URL-safe, collision-resistant Nano IDs with a custom size and alphabet.

Images

• Image Optimizer — Re-encode and shrink images (JPEG/WebP/PNG), optionally resizing.
• Image Format Converter — Convert images between PNG, JPEG and WebP entirely in your browser.
• EXIF Viewer & Remover — View and strip EXIF metadata (including GPS) from photos — nothing is uploaded.
• Base64 Image Encoder / Decoder — Convert images to Base64 Data URIs with ready-made HTML and CSS snippets, or decode a Data URI back to a downloadable image.
• App Icon Generator — Turn one image into every iOS, macOS and Android app icon size — downloaded as a ZIP, in your browser.
• Sprite Sheet CSS Animation Generator — Turn a sprite sheet into a copy-paste CSS @keyframes animation using steps(), with a live preview.
• SVG to PNG Converter — Convert SVG to PNG or JPG at any scale, with a transparent or solid background, in your browser.
• Image Color Picker — Upload an image and pick colors from any pixel to get HEX, RGB and HSL values, in your browser.
• Color Format Converter — Convert a color across HEX, RGB, HSL, HWB, LAB, LCH and OKLCH with a live swatch.
• Barcode Generator — Generate EAN, UPC, Code 128 and Code 39 barcodes and download them as SVG or PNG.
• Image Color Palette Extractor — Extract a dominant color palette from an image as HEX, RGB and HSL with CSS variables.
• Flip & Rotate Image — Rotate by 90° and flip images horizontally or vertically, then download — in your browser.
• Image Cropper — Crop an image to any area or fixed aspect ratio and download it, in your browser.
• Image Watermark — Add a text or logo watermark to an image, anchored or tiled, with opacity and rotation.
• Blur & Redact Image — Permanently blur, pixelate or black out parts of a screenshot before sharing it.
• Round Image Corners — Clip photos to rounded rectangles or circles and export PNGs with transparent corners.
• Color Blindness Simulator — See any image the way people with protanopia, deuteranopia or tritanopia see it.
• Image DPI Changer — Set a PNG or JPEG’s DPI for print without recompressing a single pixel.

Video

• Video Compressor — Compress video files in your browser — adjustable quality, resolution and format, nothing uploaded.
• Video Converter — Convert MOV, MKV, AVI, WebM and MP4 videos to MP4 or WebM in your browser — nothing uploaded.
• Video Trimmer — Cut a clip from a video by start and end time, in your browser — nothing uploaded.
• Extract Audio from Video — Extract the audio from a video as MP3, WAV or M4A, in your browser — nothing uploaded.
• Mute Video — Remove the audio track from a video in your browser — nothing uploaded.
• Add Music / Replace Audio — Replace the audio in a video with your own music and adjust the volume, in your browser.
• Video Resizer — Resize video for Reels, YouTube, square and more with letterboxing, in your browser.
• Crop Video — Crop a video to square, vertical or landscape and trim the edges, in your browser.
• Video to GIF — Turn a clip of a video into an optimized animated GIF, in your browser — nothing uploaded.
• GIF to Video — Convert an animated GIF to MP4 or WebM for smaller size and easy sharing, in your browser.
• Video Thumbnail Generator — Auto-generate still frames from a video and download them as JPG, PNG or WebP.
• Screenshot from Video — Capture the current frame of a video as a PNG, JPEG or WebP image, in your browser.
• Split Video — Split a video into multiple parts by time or count and download them as a ZIP, in your browser.
• Add Watermark to Video — Overlay a text or logo watermark on a video with position and opacity control, in your browser.
• Video Speed Changer — Speed up or slow down a video, re-timing the audio to match, in your browser.
• Video Merger — Join clips into one video — lossless when they match, auto-scaled to MP4 when not.
• Audio Converter — Convert audio between MP3, WAV, FLAC, M4A and OGG with bitrate control.

PDF

• Image to PDF — Combine images into a single PDF (auto / portrait / landscape).
• PDF to Images — Render PDF pages to PNG or JPG images you can download.
• Merge PDFs — Combine multiple PDFs into one, with reordering.
• Split PDF — Extract pages or ranges (e.g. 1-3,5,7-9) into a new PDF.
• Rotate PDF — Rotate all pages or a selection by 90/180/270°.
• Organize PDF — Reorder, rotate and delete pages from thumbnails, then export.
• Add Page Numbers — Stamp page numbers onto a PDF (position, format, start).
• Watermark PDF — Add a diagonal text watermark to every page.
• Crop PDF — Trim margins from every page via the crop box.
• PDF to Text — Extract selectable text from a PDF as plain text or Markdown.
• Compare PDFs — Diff the extracted text of two PDFs line-by-line.
• Encrypt PDF — Password-protect a PDF with AES-256 or RC4 encryption.
• Decrypt PDF — Remove password protection from an encrypted PDF.
• Compress PDF — Shrink a PDF by re-rendering each page to a JPEG at a chosen quality and resolution.
• PDF Metadata Editor — View, edit or strip a PDF’s title, author, subject, keywords and producer.
• Resize PDF — Rescale every PDF page to A4, Letter or another standard size, content centred.

Date / Time

• Unix Timestamp Converter — Convert between Unix timestamps and human dates (local + UTC).
• UUID Generator — Generate one or many random UUID v4 values.
• Cron Explainer — Explain a cron expression and preview its next run times.
• World Clock & Time Zone Converter — Compare times across cities on an aligned 24-hour grid and plan meetings — right in your browser.
• Cron Expression Generator — Visually build a cron expression with live preview, a plain-English summary and next run times.
• Date Duration Calculator — Calculate the duration between two dates in years, months, weeks, days and business days.
• Age Calculator — Calculate exact age in years, months and days as of any date, plus totals in weeks, days, hours and next birthday.
• Duration Converter — Convert a duration between seconds, minutes, hours, days, HH:MM:SS and human formats.
• Business Days Calculator — Add or subtract working days from a date, or count business days between two dates.
• Date Calculator — Add or subtract years, months, weeks and days from a date to find the resulting date.
• Time Duration Calculator — Calculate the hours and minutes between two times of day, even across midnight.
• ISO Week Number Calculator — Find the ISO-8601 week number for any date, and the date range for a given week.
• strftime Date Formatter — Format a date with strftime tokens (%Y, %m, %d…) and preview the output live.
• Relative Time Formatter — Turn a date into a human "time ago" phrase, or humanize a duration.
• Time Calculator — Add or subtract times and durations, and sum multiple time spans.
• Time Card Calculator — Total daily and weekly work hours from clock-in/out times minus breaks.
• Day of the Week Calculator — Find the day of the week for any date, past or future.
• Sunrise & Sunset Calculator — Sunrise, sunset, solar noon, twilight and golden hour for any date and location.
• Moon Phase Calculator — Moon phase, illumination and age for any date, with a full-month phase calendar.

Web & DevOps

• Chmod Calculator — Convert Unix file permissions between octal and symbolic (rwx).
• .gitignore Generator — Build a .gitignore from common language and tool templates.
• HTTP Status & MIME Types — Searchable reference of HTTP status codes and MIME content types.
• Open Graph Generator — Generate Open Graph & Twitter meta tags with a live social-card preview.
• robots.txt Generator — Visually build a robots.txt with user-agent rules, allow/disallow paths, crawl-delay and sitemaps.
• XML Sitemap Generator — Turn a list of URLs into a standards-compliant sitemap.xml with optional lastmod, changefreq and priority.
• .htaccess Generator — Toggle and configure common Apache .htaccess snippets with live output.
• Nginx Config Generator — Build an nginx server block (static, reverse proxy, SSL, gzip, caching) from simple toggles.
• Semver Calculator — Parse, compare, range-check, increment, and coerce semantic versions.
• Cache-Control Header Builder — Assemble a correct HTTP Cache-Control header from plain toggles and human time units, with copy-ready nginx, Apache, and meta snippets.
• Meta Tag Generator — Generate SEO, Open Graph and Twitter Card meta tags for your page from a simple form.
• CSP Header Generator — Build a Content-Security-Policy header from directive toggles, with report-only and copy output.
• htpasswd Generator — Generate Apache/nginx .htpasswd entries with bcrypt or SHA-1 hashed passwords, in your browser.
• Tailwind Color Generator — Generate a full 50-950 Tailwind color scale from one brand color, with config-ready output.
• CSS Grid Generator — Build CSS grid layouts visually and copy grid-template-columns, rows and gap.
• CSS Clamp Calculator — Calculate a fluid CSS clamp() value from min and max sizes and viewport widths.
• Cubic Bezier Generator — Design a cubic-bezier() easing curve with draggable handles and an animated preview.
• Redirect Map Generator — Turn an old-to-new URL list into 301 redirect rules for nginx, Apache, Netlify and Vercel.
• JSON-LD Generator — Generate schema.org JSON-LD structured data for Article, Product, FAQ and more from a form.
• Query String to JSON — Convert a URL query string to JSON and back, handling nested keys and repeated params.
• HTML to JSX Converter — Convert HTML to valid React JSX: className, style objects, self-closing tags and camelCase.
• CSS Gradient Generator — Design linear, radial and conic CSS gradients with live color stops and copy the code.
• CSS Box Shadow Generator — Build layered CSS box-shadow values with a live preview and copyable code.
• CSS Border Radius Generator — Create simple or per-corner CSS border-radius, including blob shapes, with a live preview.
• .editorconfig Generator — Generate an .editorconfig from indent, charset and newline options with per-language overrides.
• Aspect Ratio Calculator — Simplify ratios, solve missing dimensions and fit sizes into boxes, with CSS output.

Network

• CIDR / Subnet Calculator — Calculate network, broadcast, host range and mask from a CIDR block.
• IPv6 ↔ IPv4 Converter — Convert between IPv4 and IPv6 (mapped/expanded/compressed) and extract embedded IPv4.
• User Agent Parser — Parse a User-Agent string into browser, engine, operating system and device, in your browser.
• HAR File Viewer — Open a HAR file and inspect the request waterfall, headers, timings and sizes, in your browser.
• IP Range to CIDR — Convert a start and end IP address into the minimal set of CIDR blocks, and back.
• Set-Cookie Parser — Parse Set-Cookie and Cookie headers into a readable table of names, values and attributes.
• IP Address to Integer Converter — Convert an IPv4 or IPv6 address to its integer, hex and binary form, and back.
• MAC Address Generator — Generate random or vendor-prefixed MAC addresses in several formats.
• WiFi QR Code Generator — Create a scannable QR code that joins a WiFi network, with correct escaping.
• Download Time Calculator — Estimate how long a file takes to transfer at a given connection speed.
• DMARC Record Generator — Build and validate a DMARC DNS TXT record with policy, reporting and alignment.
• SPF Record Generator — Build and validate the SPF TXT record that stops others sending mail as your domain.
• Port Number Lookup — What runs on a TCP or UDP port — search by number or service name.
• Data Usage Calculator — Turn streaming, browsing and call habits into monthly gigabytes and cap forecasts.

API Tools

• cURL to Fetch — Convert a curl command to a JavaScript fetch() call.
• URL Parser — Break a URL into its parts and list query parameters.
• API Request Client — Send HTTP requests, build headers and params, inspect responses — your last 25 requests are saved locally.
• URL Builder & UTM Generator — Construct and validate fully encoded production URLs with standard analytics query flags (UTM) or custom query arrays.
• OpenAI API Tester — Build, run and copy OpenAI Chat Completions API requests as cURL, Python and JavaScript.
• Anthropic Claude API Tester — Build, run and copy Anthropic Claude Messages API requests as cURL, Python and JavaScript.
• Google Gemini API Tester — Build, run and copy Google Gemini generateContent API requests as cURL, Python and JavaScript.
• Replicate API Tester — Build, run and copy Replicate prediction API requests as cURL, Python and JavaScript.
• Hugging Face API Tester — Build, run and copy Hugging Face Inference API requests as cURL, Python and JavaScript.
• cURL to Python — Convert a curl command to Python requests code.
• cURL to Go — Convert a curl command to Go net/http code.
• cURL to PHP — Convert a curl command to PHP cURL code.
• cURL to Node.js (axios) — Convert a curl command to Node.js axios code.
• Token Counter — Count tokens for GPT, Claude and Gemini live — exact OpenAI counts plus Claude/Gemini estimates.
• LLM API Cost Calculator — Estimate GPT, Claude and Gemini API costs from token counts, with custom price overrides.
• cURL to Rust — Convert a curl command to Rust reqwest code.
• HAR to cURL — Turn requests from a browser HAR file into runnable cURL commands, with secrets stripped.
• Postman to cURL — Turn a Postman collection export into runnable cURL commands, variables resolved.

Security

• JWT Decoder — Decode JWT header & payload and inspect exp / iat (no verification).
• Hash Generator — SHA-256 / SHA-1 / SHA-384 / SHA-512 via the Web Crypto API.
• Password Generator — Generate strong, random passwords with a strength meter (crypto-secure).
• SSH Key Generator — Generate Ed25519, RSA or ECDSA SSH keypairs in your browser and download the public and private keys.
• PPK ↔ PEM Converter — Convert SSH private keys between PuTTY .ppk and OpenSSH/PEM (RSA & Ed25519) — locally in your browser.
• TOTP / 2FA Generator — Generate time-based one-time passwords (2FA codes) from a base32 secret.
• JWT Signer — Create and sign a JWT (HS256/384/512) from a payload and secret — Web Crypto.
• Basic Auth Generator — Generate and decode HTTP Basic Auth Authorization headers from a username and password.
• Certificate & Private Key Matcher — Confirm an X.509 certificate or CSR and a private key belong together (the classic modulus mismatch check) — locally in your browser.
• PFX to PEM Extractor — Open a password-protected .pfx/.p12 file and split it into certificate, chain, and private-key PEM blocks.
• Bcrypt Generator — Hash a password with bcrypt and verify a password against a bcrypt hash, in your browser.
• HMAC Generator — Generate an HMAC (SHA-256, SHA-1, SHA-512) from a message and secret key using Web Crypto.
• Password Strength Checker — Check password strength with entropy, character-set and common-pattern analysis, in your browser.
• X.509 Certificate Decoder — Decode a PEM or DER certificate to view subject, issuer, validity, SANs and fingerprints.
• Diceware Passphrase Generator — Generate a memorable, high-entropy passphrase from the EFF word list, in your browser.
• CSP Analyzer — Parse a Content-Security-Policy header into a directive table with warnings and explanations.
• File Hash Checksum — Compute MD5, SHA-1, SHA-256 and SHA-512 checksums of files and compare against an expected hash.
• IBAN Generator & Validator — Generate valid test IBANs by country and validate any IBAN with MOD-97 check digits.
• AES Encrypt / Decrypt — Encrypt and decrypt text with AES-GCM and a passphrase, using Web Crypto in your browser.
• SHA-3 & Keccak Hash Generator — Hash text or hex with SHA-3, Keccak-256 and SHAKE, for Ethereum and general use.
• MD5 Hash Generator — Generate an MD5 hash of text or a file, in your browser.
• CRC32 Checksum Calculator — Compute a CRC32 checksum of text as hex and decimal, in your browser.
• CSR Decoder — Read a certificate signing request: subject, SANs, key size and signature check.

Geo / Maps

• Coordinate Map Viewer — Plot a latitude/longitude on an OpenStreetMap map, or click the map to read coordinates back out.
• GPX to GeoJSON — Convert GPX to GeoJSON and back — GPS tracks, routes and waypoints to GeoJSON features, or GeoJSON back to a GPX file.
• KML to GeoJSON — Convert KML ⇄ GeoJSON — turn Google Earth KML into GeoJSON for web maps, or GeoJSON back into KML.
• WKT to GeoJSON — Convert WKT (Well-Known Text) to GeoJSON and back, in your browser.
• GeoJSON to CSV — Convert a GeoJSON FeatureCollection to CSV and back — Point features become latitude/longitude columns with their properties.
• Plus Codes Converter — Convert between latitude/longitude and a Plus Code (Open Location Code) both ways, with the covered bounding box and cell size.
• MGRS Converter — Convert between latitude/longitude and MGRS (Military Grid Reference System) coordinates, both ways, in your browser.
• Distance Between Coordinates — Measure the great-circle distance between two latitude/longitude points in km, miles and nautical miles, with bearing and a map.
• GPX Viewer — Open a GPX file and see its tracks, routes and waypoints on a map, with distance, elevation and bounds.
• Coordinate Converter (DMS & Decimal) — Convert coordinates between decimal degrees, DMS and degrees-decimal-minutes, both ways, in your browser.
• Geohash Converter — Encode latitude/longitude to a geohash and decode a geohash back to coordinates, with bounding box and neighbors.
• Polyline Encoder & Decoder — Encode coordinates to a Google encoded polyline string and decode polylines back to coordinates or GeoJSON.
• GeoJSON Viewer & Validator — Paste or drop GeoJSON to validate it and see its features on a map, with feature counts and a bounding box.
• UTM Converter — Convert between latitude/longitude and UTM coordinates (zone, hemisphere, easting, northing) on the WGS84 ellipsoid.
• GeoJSON Bounding Box — Get the bounding box, centre, area and length of any GeoJSON, in both coordinate orders.
• GeoJSON Simplify — Thin dense GeoJSON lines and polygons with Douglas–Peucker at a metre tolerance.

Programmatic Ads

• VAST Validator — Validate VAST 2.0-4.3 ad XML against IAB rules and see errors and warnings, in your browser.
• VAST Tag Inspector — Inspect a VAST tag as a readable tree of creatives, media files and tracking events.
• VAST Error Code Lookup — Look up any VAST or VPAID error code (100-901) with its meaning, cause and fix.
• VAST Macro Expander — Browse VAST 4.x macros and expand a tracking URL with sample or custom values.
• VMAP Validator — Validate VMAP ad-break XML and see the ad-break timeline, in your browser.
• OpenRTB Bid Request Validator — Validate an OpenRTB 2.5 or 2.6 bid request for missing fields, wrong types and bad enums.
• OpenRTB Bid Request Generator — Build a valid OpenRTB 2.5 or 2.6 bid request JSON from a form, with CTV presets.
• OpenRTB Enum Reference — Search OpenRTB objects and enums like devicetype, api, protocols and plcmt.
• TCF Consent String Decoder — Decode an IAB TCF v2.2 consent string into purposes, vendors and legitimate interest.
• GPP String Decoder — Decode an IAB GPP string into its header and each embedded consent section.
• US Privacy String Decoder — Decode a US Privacy (CCPA) string like 1YNN into plain-language opt-out fields.
• TCF Consent String Encoder — Build an IAB TCF v2.2 consent string from purposes, vendors and CMP fields.
• ads.txt Validator — Validate ads.txt and app-ads.txt records against the IAB spec, line by line.
• sellers.json Validator — Validate a sellers.json document against the IAB spec and flag every error.
• SupplyChain (schain) Builder — Build and validate an OpenRTB SupplyChain object and its serialized schain string.
• CPM Calculator — Calculate CPM, impressions or media cost from any two values, both ways.
• eCPM Calculator — Calculate eCPM from ad earnings and impressions, or reverse-solve either input.
• Fill Rate Calculator — Calculate ad fill rate from requests and impressions served, with unfilled counts.
• IAB Ad Size Reference — Look up IAB standard ad unit sizes by name or dimensions, like 300x250 and 728x90.
• Prebid Ad Unit Generator — Generate a Prebid.js ad unit config with media types, sizes and bidder params.
• CTR Calculator — Calculate click-through rate, clicks or impressions from any two values.
• ROAS Calculator — Calculate return on ad spend, revenue or ad cost, with break-even ROAS.

Finance

• Mortgage Calculator — Estimate monthly mortgage payments including principal, interest, taxes and insurance.
• Loan Calculator — Calculate the monthly payment, total interest and payoff of any amortized loan.
• Amortization Calculator — Build a full loan amortization schedule showing principal and interest for each payment.
• Auto Loan Calculator — Estimate car loan payments with trade-in, down payment and sales tax.
• Mortgage Payoff Calculator — See how extra payments shorten your mortgage and cut total interest.
• Refinance Calculator — Compare your current mortgage to a refinance and find the break-even point.
• APR Calculator — Find the true annual percentage rate of a loan once fees are included.
• Down Payment Calculator — Work out the down payment, loan amount and how long to save for it.
• House Affordability Calculator — Estimate the home price you can afford from income, debts and down payment.
• Debt-to-Income Ratio Calculator — Calculate your front-end and back-end debt-to-income (DTI) ratios.
• HELOC Calculator — Estimate a home equity line of credit limit and interest-only or amortized payments.
• Home Equity Loan Calculator — Estimate how much you can borrow against home equity and the monthly payment.
• FHA Loan Calculator — Estimate FHA mortgage payments including upfront and monthly mortgage insurance.
• Rent vs. Buy Calculator — Compare the total cost of renting versus buying a home over time.
• Rent Affordability Calculator — Find how much rent you can afford from your income using the 30% rule.
• Student Loan Calculator — Estimate student loan monthly payments, payoff time and total interest.
• Personal Loan Calculator — Estimate personal loan payments, APR impact and total repayment.
• Business Loan Calculator — Estimate business loan payments with fees and see the true borrowing cost.
• Credit Card Payoff Calculator — See how long it takes to pay off a credit card and the interest you will pay.
• Debt Payoff Calculator — Plan a debt-free date with the avalanche or snowball method across multiple debts.
• Debt Consolidation Calculator — Compare multiple debts to a single consolidation loan and see the savings.
• Auto Lease Calculator — Estimate a car lease monthly payment from price, residual and money factor.
• Interest Rate Calculator — Solve for the interest rate of a loan from its amount, payment and term.
• Simple Interest Calculator — Calculate simple interest and the final amount from principal, rate and time.
• Credit Card Calculator — Estimate the payoff time and interest for a credit card balance.
• Compound Interest Calculator — Project savings growth with compound interest and optional regular contributions.
• Savings Calculator — See how a starting balance plus regular deposits grow with interest over time.
• Investment Calculator — Solve for the ending amount, return, contribution or time of an investment.
• CD Calculator — Calculate the maturity value and APY of a certificate of deposit.
• ROI Calculator — Calculate return on investment, net gain and annualized ROI.
• IRR Calculator — Compute the internal rate of return and NPV from a series of cash flows.
• Present Value Calculator — Find the present value of a future sum or cash flow stream at a discount rate.
• Future Value Calculator — Find the future value of a present sum or a stream of payments.
• Annuity Calculator — Calculate the accumulated value or payment of an annuity over time.
• Annuity Payout Calculator — Find the regular payout a lump sum can provide over a set period.
• Bond Calculator — Calculate a bond price, current yield and yield to maturity.
• CAGR Calculator — Calculate the compound annual growth rate and average return of an investment.
• Payback Period Calculator — Find how long an investment takes to pay back from its cash flows.
• Mutual Fund Fee Calculator — See how expense ratios and fees erode mutual fund returns over time.
• Retirement Calculator — Estimate whether your savings and contributions will fund your retirement.
• 401(k) Calculator — Project 401(k) growth with employer match and contribution limits.
• Roth IRA Calculator — Project tax-free Roth IRA growth from contributions and returns.
• IRA Calculator — Compare traditional IRA growth before and after tax at withdrawal.
• Pension Calculator — Estimate a defined-benefit pension from salary, service years and accrual rate.
• RMD Calculator — Estimate required minimum distributions from a retirement account.
• Finance Calculator (TVM) — Solve any time-value-of-money variable: PV, FV, payment, rate or periods.
• Interest Calculator — Calculate simple or compound interest and the total from principal, rate and time.
• Inflation Calculator — Project how inflation changes the buying power of money over time.
• College Cost Calculator — Project future college costs and the savings needed to cover them.
• Rental Property Calculator — Analyze a rental property cash flow, cap rate and cash-on-cash return.
• Sales Tax Calculator — Add or remove sales tax and find the tax amount, pre-tax price or total.
• VAT Calculator — Add or remove VAT and see the net price, VAT amount and gross total.
• Income Tax Calculator — Estimate US federal income tax, effective rate and take-home from taxable income.
• Salary Calculator — Convert pay between hourly, daily, weekly, monthly and annual amounts.
• Profit Margin Calculator — Calculate profit margin, markup, revenue or cost from any two values.
• Markup Calculator — Calculate the selling price and profit from cost and markup percentage.
• Discount Calculator — Find the sale price and amount saved from an original price and discount.
• Commission Calculator — Calculate sales commission, take-home and effective rate on a sale.
• Depreciation Calculator — Compute asset depreciation with straight-line, declining balance or SYD.
• Budget Calculator — Split monthly income into needs, wants and savings with the 50/30/20 rule.
• Tip Calculator — Calculate the tip and total, and split the bill between people.
• GDP Calculator — Calculate GDP by the expenditure approach and real vs nominal GDP.
• VA Mortgage Calculator — Estimate a VA loan payment including the VA funding fee and no PMI.
• Payment Calculator — Solve a loan monthly payment or the term needed to pay it off.

Health & Fitness

• BMI Calculator — Calculate body mass index and see the healthy weight range for your height.
• BMR Calculator — Estimate your basal metabolic rate — the calories your body burns at rest.
• TDEE Calculator — Estimate total daily energy expenditure from BMR and activity level.
• Calorie Calculator — Estimate daily calories to maintain, lose or gain weight from your stats.
• Macro Calculator — Split your daily calories into protein, carbs and fat grams by ratio.
• Protein Calculator — Estimate your daily protein needs from weight and activity level.
• Carbohydrate Calculator — Estimate daily carbohydrate grams from your calories and diet split.
• Fat Intake Calculator — Estimate daily dietary fat grams from your calories and target percentage.
• Body Fat Calculator — Estimate body fat percentage with the US Navy tape measurement method.
• Army Body Fat Calculator — Estimate body fat with the US Army (AR 600-9) circumference method.
• Lean Body Mass Calculator — Estimate lean body mass and fat mass from height, weight and sex.
• Ideal Weight Calculator — Estimate ideal body weight with the Devine, Robinson, Miller and Hamwi formulas.
• Healthy Weight Calculator — Find the healthy weight range for your height from the normal BMI band.
• Body Type Calculator — Estimate your body shape from bust, waist and hip measurements.
• Body Surface Area Calculator — Estimate body surface area (BSA) with Mosteller, Du Bois and other formulas.
• Calories Burned Calculator — Estimate calories burned by activity using MET values, weight and time.
• Pace Calculator — Calculate running pace, time or distance and convert between pace units.
• One Rep Max Calculator — Estimate your one-rep max from a weight and reps with several formulas.
• Target Heart Rate Calculator — Find your target heart-rate training zones from age and resting rate.
• GFR Calculator — Estimate glomerular filtration rate (eGFR) with the CKD-EPI 2021 equation.
• BAC Calculator — Estimate blood alcohol content from drinks, weight, sex and time.
• Due Date Calculator — Estimate a pregnancy due date from the last menstrual period (Naegele’s rule).
• Pregnancy Calculator — Track pregnancy progress, trimester and milestones from the due date or LMP.
• Ovulation Calculator — Estimate your fertile window and ovulation day from your cycle.
• Conception Calculator — Estimate the likely conception date from a due date or last period.
• Period Calculator — Predict your next several periods and fertile windows from your cycle.
• Pregnancy Weight Gain Calculator — Estimate a healthy pregnancy weight-gain range from pre-pregnancy BMI.
• Pregnancy Conception Calculator — Estimate the conception date and fertile window from a known pregnancy.
• Water Intake Calculator — Daily water target from weight, exercise and climate, in glasses and bottles.

Math

• Percentage Calculator — Solve percentage problems: X% of Y, X is what % of Y, and percent change.
• Fraction Calculator — Add, subtract, multiply and divide fractions and simplify the result.
• Percent Error Calculator — Calculate percent error between an experimental and true value.
• Exponent Calculator — Raise a base to any power, including negative and fractional exponents.
• Log Calculator — Compute logarithms in any base, plus natural log and log base 10.
• Root Calculator — Find square roots, cube roots and any nth root of a number.
• Quadratic Formula Calculator — Solve quadratic equations ax²+bx+c=0 with real or complex roots and steps.
• Ratio Calculator — Simplify ratios and solve proportions for a missing value.
• Rounding Calculator — Round numbers to decimals, significant figures or the nearest multiple.
• Scientific Notation Converter — Convert numbers to and from scientific, e-notation and engineering notation.
• LCM Calculator — Find the least common multiple of two or more integers with the steps.
• GCF Calculator — Find the greatest common factor of two or more integers with the steps.
• Factor Calculator — List all factors of a number and its prime factorization.
• Triangle Calculator — Solve a triangle from sides and angles, with area, perimeter and type.
• Right Triangle Calculator — Solve a right triangle from any two sides or a side and an angle.
• Pythagorean Theorem Calculator — Find a missing side of a right triangle with a²+b²=c².
• Area Calculator — Calculate the area of circles, rectangles, triangles, trapezoids and more.
• Volume Calculator — Calculate the volume of spheres, cylinders, cones, boxes and more.
• Surface Area Calculator — Calculate the surface area of spheres, cylinders, cones, boxes and more.
• Circle Calculator — Find a circle’s radius, diameter, circumference and area from any one value.
• Standard Deviation Calculator — Calculate population and sample standard deviation, variance and mean of a data set.
• Mean, Median, Mode, Range Calculator — Find the mean, median, mode and range of a list of numbers.
• Statistics Calculator — Compute full descriptive statistics for a data set — mean, SD, quartiles and more.
• Probability Calculator — Calculate probabilities of single and combined events, including conditional.
• Permutation and Combination Calculator — Calculate permutations (nPr) and combinations (nCr) for n and r.
• Z-score Calculator — Convert a value to a z-score and find the probability from the normal distribution.
• Confidence Interval Calculator — Compute a confidence interval for a mean from sample statistics.
• Sample Size Calculator — Find the survey sample size needed for a confidence level and margin of error.
• Slope Calculator — Find the slope, intercept, distance and equation of a line through two points.
• Distance Calculator — Calculate the distance between two points in 2D or 3D space.
• Number Sequence Calculator — Find terms and sums of arithmetic, geometric and Fibonacci sequences.
• Half-Life Calculator — Solve half-life, decay time, and remaining quantity of a decaying substance.
• Big Number Calculator — Do exact arithmetic on very large integers beyond normal precision.
• Binary Calculator — Add, subtract, multiply and divide binary numbers and convert to decimal/hex.
• Hex Calculator — Add, subtract, multiply and divide hexadecimal numbers and convert bases.
• Matrix Calculator — Add, multiply, transpose and find the determinant and inverse of matrices.
• Scientific Calculator — A full scientific calculator for trig, logs, powers, roots and constants.
• Random Number Generator — Generate random numbers in a range, with unique values, decimals and count.

Science

• Density Calculator — Solve density, mass or volume from the density formula ρ = m/V.
• Mass Calculator — Calculate mass from density and volume, or from force and acceleration.
• Weight on Planets Calculator — Find your weight on the Moon and other planets from mass and gravity.
• Speed Calculator — Solve speed, distance or time and convert between mph, km/h and m/s.
• Molarity Calculator — Solve molarity, moles or volume for a solution (M = mol/L).
• Molecular Weight Calculator — Compute the molar mass of a chemical formula like H2O or C6H12O6.
• Ohm’s Law Calculator — Solve voltage, current, resistance and power from any two values.
• Resistor Color Code Calculator — Convert resistor color bands to resistance and back, with tolerance.
• Voltage Drop Calculator — Estimate voltage drop over a wire run from gauge, length and current.
• Electricity Cost Calculator — Estimate the energy use and running cost of an appliance.
• Wind Chill Calculator — Calculate the wind chill “feels like” temperature from temperature and wind.
• Heat Index Calculator — Calculate the heat index “feels like” temperature from heat and humidity.
• Dew Point Calculator — Calculate the dew point from temperature and relative humidity.
• Ideal Gas Law Calculator — Solve PV = nRT for pressure, volume, moles or temperature in any common unit.
• pH Calculator — Convert between pH, pOH and ion concentration, and find the pH of weak acids and buffers.
• Wavelength & Frequency Converter — Convert wavelength, frequency and photon energy, with spectrum band and refractive index.
• Projectile Motion Calculator — Range, apex, flight time and impact for a launch at any speed, angle and height.
• Dilution Calculator — C₁V₁ = C₂V₂ solved for any variable, plus serial dilution planning for the bench.

Construction

• Concrete Calculator — Estimate concrete volume and bags for slabs, footings and columns.
• BTU Calculator — Estimate the BTU capacity needed to heat or cool a room.
• Square Footage Calculator — Calculate area in square feet or meters for rooms and projects, with cost.
• Stair Calculator — Calculate stair rise, run, number of steps and stringer length to code.
• Roofing Calculator — Estimate roof area, squares and shingle bundles from footprint and pitch.
• Tile Calculator — Calculate how many tiles and boxes you need for a floor or wall.
• Mulch Calculator — Estimate mulch volume in cubic yards and bags for a bed and depth.
• Gravel Calculator — Estimate gravel volume and weight in tons for an area and depth.
• Paint Calculator — Work out how much paint a room needs from its size, coats, doors and windows.
• Brick Calculator — Estimate bricks and mortar for a wall from its size, brick type and joint width.
• Board Foot Calculator — Calculate board feet and lumber cost for a cut list of boards.
• Drywall Calculator — Estimate drywall sheets, joint compound, tape and screws for a room.
• Wallpaper Calculator — Rolls needed from wall size, roll size and pattern repeat, the way decorators count.
• Fence Calculator — Posts, rails, pickets and concrete bags for a fence run, using the fencepost rule.

Automotive

• Fuel Cost Calculator — Estimate the fuel cost of a trip from distance, efficiency and price.
• Gas Mileage Calculator — Calculate MPG or L/100km from distance and fuel used, and convert.
• Mileage Reimbursement Calculator — Calculate mileage reimbursement from miles driven and a per-mile rate.
• Horsepower Calculator — Calculate horsepower from torque and RPM, or convert power units.
• Engine Horsepower Calculator — Estimate engine horsepower from quarter-mile ET or trap speed.
• Tire Size Calculator — Decode a tire size and compare two sizes for diameter and speedo error.
• VIN Decoder — Decode a 17-character VIN into maker, country, model year and plant, and verify its check digit.
• Fuel Economy Converter — Convert between MPG (US), MPG (UK), L/100km and km/L, with trip fuel and cost.
• Gear Ratio Calculator — Work out speed at RPM, RPM at speed and gear ratios from tooth counts and tyre size.
• Engine Displacement Calculator — Calculate engine displacement in cc, litres and cubic inches from bore, stroke and cylinders.
• Braking Distance Calculator — Stopping distance from speed, reaction time and road surface — thinking plus braking.
• EV Charging Cost Calculator — What a charge costs from battery size, charge window and electricity price, vs petrol.

Everyday

• GPA Calculator — Calculate your grade point average from course grades and credit hours.
• Grade Calculator — Compute a weighted course grade and the score needed on the final exam.
• Sleep Calculator — Find the best bedtimes or wake times based on 90-minute sleep cycles.
• Golf Handicap Calculator — Estimate a golf handicap index from your recent scores and course data.
• Dice Roller — Roll any number and type of dice (d4–d20) with modifiers and totals.
• Shoe Size Converter — Convert shoe sizes between US, UK, EU and centimeters for men and women.
• Bra Size Calculator — Estimate your bra size from band and bust measurements in US, UK and EU.
• Unit Conversion Calculator — Convert length, weight, temperature, volume, area, speed and more.
• Height Calculator — Convert height between feet/inches and cm, and predict a child’s adult height.
• Cooking Measurement Converter — Convert cups, spoons, millilitres, grams and ounces using ingredient density.
• Pet Age Calculator — Convert dog and cat years to human years using size-adjusted ageing curves.
• Ring Size Converter — Convert ring sizes between US, UK, EU, Japan, diameter and circumference.
• Clothing Size Converter — Convert women’s and men’s clothing sizes between US, UK, EU, Italian and French charts.
• Unit Price Calculator — Compare pack sizes by price per 100 g, 100 ml or piece and spot the real bargain.
• Chinese Zodiac Calculator — Your animal sign and element from your birth date, honouring Chinese New Year cutoffs.

Online developer tools without the privacy risk

Most online utilities make you paste sensitive data, upload files or process private content on remote servers. ArrayKit is designed for developers, QA, DevOps, support and technical teams who need fast tools for JSON, PDFs, images, API debugging, encoding, security checks and formatting — with a privacy-first, browser-based approach.

Frequently asked questions

Can I use ArrayKit tools right away?

Yes. The core browser-based tools are available online and you can start using them instantly, right in your browser, with nothing to install.

Do I need an account to use ArrayKit?

You can use the core browser-based tools right away. Optional account features are planned for saved preferences, favorites, history and team workflows.

Does ArrayKit upload my files or text?

ArrayKit is built around browser-based processing: tools run locally on your device, so your content does not need to be uploaded to a server.

Who is ArrayKit for?

Developers, QA engineers, DevOps and support teams, data analysts — anyone who works with JSON, PDFs, images, APIs, text, encoders, formatters or security utilities.

Can I use ArrayKit for sensitive data?

ArrayKit is privacy-first and processes data in your browser, but you should still avoid pasting production secrets, private keys or passwords into any online tool unless you have verified how it works.

Do the tools work offline?

Once a tool’s page and assets have loaded, it can keep working offline, depending on your browser’s caching and the specific tool.