Which CRC-32 variant does this use?

It uses the standard IEEE 802.3 polynomial (reflected 0xEDB88820), initial value all-ones, and final XOR all-ones — the same CRC-32 used by ZIP, gzip, PNG, and Ethernet, so results match those formats and common libraries.

How can I check the result is correct?

The standard CRC check string is the ASCII text "123456789", which must produce 0xCBF43926. As another reference, the lowercase word "hello" produces 0x3495352B. Matching values confirm the implementation is correct.

Is CRC-32 a cryptographic hash?

No. CRC-32 is an error-detecting checksum designed to catch accidental corruption, not deliberate tampering. It is trivial to forge, so never use it for security, passwords, or integrity against an attacker — use SHA-256 or BLAKE3 for that.

Why is the decimal value shown as unsigned?

A CRC-32 is a 32-bit value. JavaScript bitwise operations are signed, so we mask with a right shift of zero to display the full unsigned 0 to 4294967295 range, matching what zip and gzip report.

CRC-32 Checksum Calculator

This tool computes the CRC-32 checksum of any text or raw hex bytes and shows it in both hexadecimal and unsigned decimal, updating live as you type. CRC-32 is the error-detecting checksum built into common file formats and network frames, so it is ideal for verifying data integrity or matching a checksum produced by another tool.

How it works

The calculator uses the standard IEEE 802.3 polynomial (0xEDB88820) — the reflected form of 0x04C11DB7 — the same CRC-32 used by ZIP, gzip, PNG, and Ethernet. It precomputes a 256-entry lookup table, encodes your input to bytes, then runs the table-driven algorithm: starting from 0xFFFFFFFF, each byte updates the running value via crc = (crc >>> 8) XOR table[(crc XOR byte) & 0xFF], and the final value is XORed with 0xFFFFFFFF. This matches the output of standard CRC-32 libraries.

Example and notes

Input	CRC-32 (hex)
`123456789`	cbf43926
`hello`	3495352b

So the standard check string 123456789 produces 0xCBF43926, a well-known reference value you can use to confirm any CRC-32 implementation.

CRC-32 is an error-detection checksum, not a cryptographic hash. It is trivial to forge, so use it to spot accidental corruption but never for security — use SHA-256 or BLAKE3 when integrity against tampering matters. Everything is computed in pure JavaScript in your browser; nothing is uploaded.