Developer / Checksums
CRC32 Checksum Calculator
Calculate the CRC-32 and Adler-32 checksums of text or a file, in hex and decimal, as ZIP, PNG, and gzip use them.
CRC32 Checksum Calculator: CRC-32 is a cyclic redundancy check with the IEEE 802.3 polynomial, the one used by ZIP and gzip archives, PNG images, and Ethernet frames; it detects accidental changes such as transmission errors. Adler-32 is the faster, weaker checksum inside zlib streams. Files are read in chunks, so large files are checked without loading them into memory at once. Runs 100% locally in your browser with zero server file uploads.
- Category
- Developer tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Runs entirely in your browser
CBF439263421780262091E01DEClick, drag and drop, or paste · stays on this device
CRC-32 is the IEEE 802.3 checksum used by ZIP, PNG, gzip, and Ethernet; 123456789 gives CBF43926. Checksums catch accidental corruption, not tampering: use SHA-256 to check that a download has not been changed.
Where CRC-32 appears
Every file inside a ZIP archive carries a CRC-32 of its contents, checked when it is extracted; every PNG chunk ends with one; gzip stores one for the whole file. A mismatch means the data was damaged.
To verify a download against a published hash, use the file hash tool instead.
Combining checksums
CRC-32 can be updated piece by piece: the CRC of a file read in chunks equals the CRC of the whole, which is how this tool checks large files without loading them at once.
How to use it
- Type or paste text, or choose a file.
- Read the CRC-32 in hex and decimal, and the Adler-32.
- Compare it with the checksum you expect.
Privacy & limitations
Text and files are checked in your browser; files are not uploaded.
Related tools
Frequently asked questions
What is the CRC-32 of 123456789?
CBF43926, the standard check value used to confirm an implementation is right.
Can a CRC detect tampering?
No: anyone can change data and fix up its CRC. Use a cryptographic hash such as SHA-256 to verify downloads.
Why do some tools show a different CRC-32?
There are other CRC-32 variants, such as CRC-32C used by iSCSI and some storage systems, with different polynomials; this tool uses the common IEEE one.
Free tool · runs in your browser · no account required