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CRC32 checksum calculator

Compute the CRC32 checksum of any text instantly. CRC32 is the 32-bit cyclic redundancy check used by ZIP, PNG and Ethernet, shown as 8 hex characters.

Input

CRC32 checksums are 8 hexadecimal characters. Great for spotting accidental corruption.

Nothing is uploaded. Everything is computed locally in your browser.
CRC32 digest

The digest appears below in hexadecimal.

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What CRC32 does

CRC32 treats the input as a long binary number and divides it by a fixed 33-bit polynomial (0xEDB88320 reflected), keeping the 32-bit remainder. It is superb at catching accidental corruption: burst errors, flipped bits and truncated data change the checksum with near certainty. Ethernet frames, ZIP archives and PNG chunks all carry CRC32s.

Not a security hash

CRC32 is not cryptographic: it is linear, partly reversible, and trivially forgeable. An attacker can craft a different message with the same CRC32. Never use it for integrity against adversaries, password storage or signatures; use SHA-256 instead.

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CRC32 Checksum FAQs

What is the CRC32 of '123456789'?
0xCBF43926, the standard check value. If a CRC32 implementation returns anything else for that input, it is not standard CRC32 (IEEE 802.3).
CRC32 vs MD5: which for file verification?
MD5 (or better, SHA-256). CRC32 only catches accidents; MD5-family hashes resist casual tampering, though only SHA-256 resists determined attackers.
Why do ZIP files use CRC32?
ZIP stores a CRC32 per file so unzip tools can detect corruption from bad downloads or failing disks quickly, without the cost of a cryptographic hash.
Can CRC32 produce the same value for different inputs?
Yes, collisions are easy to construct because it is only 32 bits and linear. For random data, expect a collision after about 2^16 inputs (birthday bound).
Is this computed locally?
Yes. The CRC32 here is hand-written JavaScript with a lookup table; nothing is uploaded.
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