CRC32 Checksum Calculator Online

Compute a CRC32 checksum of text or a file as hex and decimal, right in your browser. Nothing you type is uploaded.

The CRC32 Checksum Calculator runs entirely in your browser. The text you type and any file you select are processed locally on your device and are never uploaded to ArrayKit.

Built and maintained by Udit Agarwal

Open the File Hash & Checksum tool

About CRC32 Checksum Calculator

The CRC32 Checksum Calculator computes the CRC32 (IEEE 802.3) checksum of any text or file and shows it as both an 8-digit hex value and an unsigned decimal number. Paste text into the input box, or drop in a file, and the checksum updates instantly as you type. It uses the same polynomial and algorithm as ZIP archives, PNG chunks, and Ethernet frames, so the result matches what zlib's crc32(), Python's binascii.crc32, and most command-line crc32 utilities produce for the same bytes. It is handy for spot-checking that a config file, log snippet, or downloaded asset was not corrupted, or for reproducing a CRC32 value referenced in file-format documentation. Built for developers who need a quick, verifiable checksum without installing a command-line tool. Everything runs locally in your browser — the text and files you check are never uploaded.

Features

  • Computes CRC32 (IEEE 802.3) for pasted text as you type
  • Shows the checksum as 8-digit hex and as an unsigned decimal number
  • Optional file input computes the CRC32 of any local file's bytes
  • One-click copy for both the hex and decimal values
  • Matches zlib, Python, and command-line crc32 implementations exactly
  • Same polynomial ZIP, PNG, and Ethernet use, so results are cross-checkable
  • Clear note that CRC32 is an integrity check, not a cryptographic hash
  • Runs entirely in your browser — text and files are never uploaded

How to use the CRC32 Checksum Calculator

  1. Type or paste the text you want to checksum into the input box
  2. Read the CRC32 hex and decimal values, which update live
  3. Or click the file picker to compute the CRC32 of a local file instead
  4. Copy the hex or decimal value with the copy button next to each row

Example

Input

123456789

Output

CRC32 (hex): CBF43926
CRC32 (dec): 3421780262

Common errors & troubleshooting

  • My CRC32 hex value does not match what another tool printed. — Check for a trailing newline or extra whitespace in the input — CRC32 is computed over the exact bytes, so 'text' and 'text\n' produce different checksums.
  • I expected a signed number but got a large positive decimal. — The CRC32 Checksum Calculator always reports the unsigned 32-bit value (0 to 4294967295), which is the convention used by ZIP and PNG, not a signed 32-bit integer.
  • The hex value has fewer than 8 characters in another tool's output. — Some libraries drop leading zeros. This calculator always zero-pads to 8 hex digits, so 0x000004C1 will show as '000004C1' rather than '4C1'.
  • I need this checksum for security verification, not just integrity. — CRC32 is not collision-resistant and is trivial to forge deliberately — use SHA-256 or SHA-3 from the file hash tools when tamper resistance matters, not CRC32.

Frequently asked questions

What does the CRC32 Checksum Calculator compute?
It computes the CRC32 (IEEE 802.3) checksum of your text or file's bytes and shows it as an 8-digit hex string and as an unsigned decimal number, the same algorithm used by ZIP, PNG, and gzip.
Is CRC32 the same as a cryptographic hash like SHA-256?
No. CRC32 is designed to catch accidental bit errors from noisy transmission or storage, not to resist deliberate tampering. Two different inputs can be crafted to produce the same CRC32, so it should never be used for security or password checks.
Why does my CRC32 hex value have leading zeros?
CRC32 is always a 32-bit value, so this calculator zero-pads the hex output to a fixed 8 characters (e.g. '000004C1') to match how ZIP and PNG headers store it.
Does the CRC32 Checksum Calculator upload my file?
No. The CRC32 Checksum Calculator reads the file in your browser using the File API and computes the checksum locally. The file's bytes are never sent anywhere.
Why is the decimal value so large?
CRC32 produces an unsigned 32-bit integer, so the decimal value can range up to 4,294,967,295. This matches the convention used in ZIP central-directory records and most crc32 command-line tools.
Can I use this to verify a downloaded file matches a published CRC32?
Yes. Drop the downloaded file into the CRC32 Checksum Calculator and compare the hex value it shows against the checksum published by the file's source.

Related tools

  • MD5 Hash Generator — Generate an MD5 hash of text or a file, in your browser.
  • Hash Generator — SHA-256 / SHA-1 / SHA-384 / SHA-512 via the Web Crypto API.
  • File Hash Checksum — Compute MD5, SHA-1, SHA-256 and SHA-512 checksums of files and compare against an expected hash.
  • SHA-3 & Keccak Hash Generator — Hash text or hex with SHA-3, Keccak-256 and SHAKE, for Ethereum and general use.
  • HMAC Generator — Generate an HMAC (SHA-256, SHA-1, SHA-512) from a message and secret key using Web Crypto.
  • Bitwise Calculator — Apply AND, OR, XOR, NOT and bit shifts to integers, with binary, hex and decimal views.

Guides

More Security tools

  • CSR Decoder — Read a certificate signing request: subject, SANs, key size and signature check.
  • PDF Privacy Scanner — Find the metadata and personal data hiding inside a PDF.
  • Auto-Redact PDF — Find emails, phone numbers, card and ID numbers across a PDF and black them out.
  • Remove PDF Restrictions — See which actions a PDF blocks and lift the permission flags on a file you own.
  • PDF Sanitizer — Remove JavaScript, auto-run actions, embedded files and other active content from a PDF.
  • 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.

See all Security tools (27) · All tools