CRC32 Checksum Calculator

How to use

1. 1Pick Hash text or Hash a file at the top of the tool.
2. 2Type or paste text, or drop a file onto the upload area. All four CRC-32 variants compute in your browser.
3. 3Pick the featured algorithm (CRC-32, CRC-32C, BZIP2, or JAMCRC) to view its hex, decimal, byte order, and binary forms in detail.
4. 4Toggle lowercase or UPPERCASE hex, then click Copy on any value to grab it.
5. 5Paste a published CRC into the compare field to verify your file or string matches the expected value.

About this tool

CRC32 Checksum Calculator computes the 32-bit cyclic redundancy check of any text or file using the same algorithms found in ZIP archives, gzip files, PNG chunks, Ethernet frames, and many other formats. Type or paste text and the value updates as you type, or drop a file (up to 50 MB) to fingerprint it for an integrity check. The tool ships the four CRC-32 variants in real use: CRC-32 IEEE 802.3 (polynomial 0xEDB88320, the default seen in PKZip, gzip, PNG, java.util.zip, Boost.CRC, Python binascii.crc32, the Linux cksum -a crc command, and posix cksum); CRC-32C Castagnoli (polynomial 0x82F63B78, used by iSCSI, SCTP, ext4 and BTRFS metadata, Google Cloud Storage object integrity, and the Intel CRC32 SSE 4.2 hardware instruction); CRC-32/BZIP2 (polynomial 0x04C11DB7 non-reflected, used by BZIP2 archives, AIXM, and the IBM Db2 CHECKSUM function); and CRC-32/JAMCRC (the same computation as IEEE but without the final XOR, equal to the bitwise complement of standard CRC-32). Each variant is verified against the standard CRC catalog check value, which is the CRC of the ASCII string 123456789 (IEEE = 0xCBF43926, C = 0xE3069283, BZIP2 = 0xFC891918, JAMCRC = 0x340BC6D9). The output panel shows the value as lowercase or UPPERCASE hex with the 0x prefix, as unsigned decimal, as signed int32 decimal, as a 32-bit binary string in 8-bit groups, and as the four bytes in both little-endian (the wire form used inside ZIP and gzip headers) and big-endian byte order. A compare-with-expected field accepts a published CRC in any common form (0xCBF43926, CBF43926, cbf4-3926, cb f4 39 26, or an unsigned decimal) and flashes a green match or red mismatch against your selected algorithm. Useful for verifying a download against a vendor-published CRC, sanity-checking a copy between disks, hand-validating a ZIP central directory entry, debugging a CRC mismatch from a CDN or database column, generating a stable short fingerprint over a canonical string, and learning how the four variants relate. CRC-32 is excellent at catching accidental corruption but is not a cryptographic hash; do not use it where someone benefits from forging a match. Use SHA-256 or HMAC-SHA-256 from the related tools for that. Everything runs locally in your browser, so the text or file you check is never uploaded.

Free to use. Works in your browser. No signup, no login.