Adler-32 is a 32-bit checksum invented by Mark Adler in 1995. It is the default checksum in zlib (used by gzip, PNG, and many formats). It is faster than CRC32 but weaker at error detection.

Where is Adler-32 used?

zlib compression (behind gzip, PNG, and ZIP deflate), PNG images (each chunk has an Adler-32), rsync for file comparison, and some databases for lightweight validation.

CRC32 is better at detecting errors, especially burst errors. Adler-32 is faster but can miss certain patterns, particularly with short data. For general use, CRC32 is preferred.

Can Adler-32 detect all errors?

No. It can miss swapped bytes or certain multi-bit errors in very short data. It was designed as a fast 'good enough' check for compression, not a reliable error detection mechanism.

Is Adler-32 cryptographic?

No. It is a simple arithmetic checksum with zero cryptographic properties. Anyone can trivially compute a valid Adler-32 for any modified data. For security, use SHA-256 or BLAKE2.

Tools

Adler-32|8 hex chars

Input

Output

Hash result will appear here...

0 chars|0 bytes

Adler-32 Checksum Generator — zlib Fast Integrity Check

A fast 32-bit checksum used by zlib and PNG images. Faster than CRC32 but weaker at detecting errors — best for quick preliminary integrity screening of large datasets.

Features

✓Compute Adler-32 checksums online — the fast integrity check used by zlib and PNG
✓Real-time 32-bit checksum computation with 8 hex character output
✓One-click copy, download as .txt, and uppercase/lowercase toggle
✓Faster than CRC32 — ideal for quick preliminary integrity screening of large data
✓Checksum verification against known Adler-32 values
✓100% browser-based — non-cryptographic, designed for speed

How to Use

1Type or paste your text into the input box above.
2Your checksum appears instantly — no page reload needed.
3Toggle UPPERCASE / lowercase to change the hex output format.
4Click the copy icon to copy the checksum, or use Download to save as .txt.
5Paste an expected checksum into the Verify field to check for a match.

Frequently Asked Questions

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