Checksum Calculator
CRC32 and Adler-32 checksums, computed live as you type — the algorithms inside ZIP, PNG and zlib.
Checksums vs cryptographic hashes
CRC32 and Adler-32 detect accidental corruption — a flipped bit in transmission, a truncated download. They're fast but easy to forge, so for tamper-detection or passwords you want SHA-256 from our hash generator instead.
Frequently asked questions
Where is CRC32 used?
ZIP archives, PNG images, gzip, Ethernet frames and countless protocols — anywhere data needs a cheap integrity check. The standard test vector is 123456789 → CBF43926, which you can verify above.
How does Adler-32 differ?
It's the checksum inside zlib — faster than CRC32 but slightly weaker on short inputs. If you're debugging zlib streams, this is the one you're comparing against.
Is the text uploaded?
No — both checksums are computed locally in JavaScript over the UTF-8 bytes of your text.
Last updated: 2026-07-13