CRC32 and Adler-32 Checksum Calculator
Type or paste text to get its CRC32 (IEEE 802.3, polynomial 0xEDB88320) and Adler-32 checksum as both hex and decimal. Everything runs in your browser, so nothing is uploaded.
How to calculate a CRC32 checksum
- Paste or type the text you want to check.
- Read the CRC32 result as 8-character hex and as an unsigned decimal.
- Copy the value, or compare the Adler-32 output shown alongside it.
Examples
CRC32 of the standard check string
123456789
cbf43926 (decimal 3580134591)
Adler-32 of 'Wikipedia'
Wikipedia
11e60398 (decimal 300286872)
Frequently asked questions
What is CRC32 used for?
CRC32 is a fast error-detecting checksum. It is built into ZIP and gzip archives, PNG chunks, Ethernet frames and many file-transfer protocols to spot accidental corruption, so the same bytes always produce the same 32-bit value.
Which CRC32 variant does this use?
The standard IEEE 802.3 CRC32 with the reflected polynomial 0xEDB88320, computed from a precomputed 256-entry table. The well-known check value for '123456789' is 0xCBF43926, which this tool matches.
What is the difference between CRC32 and Adler-32?
Both are 32-bit checksums for detecting accidental changes. CRC32 uses polynomial division and is common in archives and networking, while Adler-32 (used in zlib) is a simpler running sum that is faster but slightly weaker on short inputs.
Is CRC32 secure for passwords or integrity against tampering?
No. CRC32 and Adler-32 detect accidental corruption, not deliberate tampering, and are easy to forge. For security use a cryptographic hash such as SHA-256 instead.
Is my text sent to a server?
No. The checksum is computed locally in your browser from the UTF-8 bytes of your input, so your text never leaves your device.
Why does an empty input still show a value?
Every byte sequence has a checksum, including the empty one. CRC32 of an empty input is 0 and Adler-32 is 1, so those values are expected rather than errors.
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