What this does
Calculates the 32-bit cyclic redundancy check of text, hex or Base64 bytes, or a file. CRC32 (the zip, gzip and PNG polynomial) and CRC32C (Castagnoli, used by iSCSI, ext4, Btrfs and Kafka) are selected by default; the other algorithms are one click away.
Reading the result
The value is shown as 8 hex digits, written big-endian as in the specification, and as an unsigned decimal. Some tools print CRC32 as a signed integer or byte-swapped; paste the value you expect into the compare box, which accepts hex (with or without 0x) or decimal.
Examples
CRC32("123456789")=cbf43926(decimal 3421780262)CRC32("The quick brown fox jumps over the lazy dog")=414fa339CRC32C("123456789")=e3069283
Files
Large files are read in chunks inside a background worker, so memory stays flat and the page stays responsive, with progress and a cancel button.
Not a security hash
A CRC catches accidental bit flips, not tampering. Use SHA-256 or BLAKE3 from thehash generator when integrity matters against an attacker.
Privacy
Everything runs locally in your browser. Nothing is uploaded.