CRC Algorithm Identifier
Result
CRC Algorithm Identifier
Already know the CRC output for this data but not which algorithm produced it? Enter the known result below — every one of the 70 catalog algorithms is recalculated against the current input data and matched against it automatically.
Enter a known CRC value to search the catalog
All 70 algorithms are checked against the current input data.
About the CRC Algorithm Identifier
Reverse engineering a protocol or file format often starts with data and a known checksum, not a documented algorithm name. The identifier recalculates the current input data against all 70 published CRC-8, CRC-16, CRC-32, and CRC-64 models in the catalog and automatically highlights every algorithm whose result matches the value you enter.
Enter the data in the calculator above, then enter the CRC result you already have in hex, decimal, octal, or binary. If more than one algorithm matches, all of them are listed — different published models can share width, polynomial, and result for a given input. If nothing matches, double-check the input data encoding and the value before assuming a custom (non-catalog) algorithm is in use.
Frequently asked questions
How do I identify which CRC algorithm produced a checksum?
Enter a sample of the data in the calculator and the checksum you already have for it, and the identifier recalculates that data under every catalog model and reports each one that reproduces your value. A single data/checksum pair is usually enough to narrow the field to a handful of models; testing a second pair from the same source eliminates the remaining coincidental matches.
Why did more than one CRC algorithm match my checksum?
Published models can produce the same result for one particular input even though they differ in initial value, reflection, or final XOR. Run a second, longer sample through the identifier — the models that only matched by coincidence will disagree on it, leaving the model your data actually uses.
What if no algorithm matches my CRC value?
Check the input encoding first, since hex, ASCII, and Base64 readings of the same field give different byte sequences, and confirm the byte order of the stored checksum, which many protocols write little-endian. Also verify you are hashing exactly the bytes the format covers — headers, length fields, and trailing padding are often included or excluded. If it still does not match, the protocol likely uses a custom parameter set rather than a published model.
Can I identify a CRC from the checksum alone?
No. A checksum on its own carries no information about which model produced it — you need the data it was calculated over as well. The width is the one exception: an 8-, 16-, or 32-bit stored value tells you the CRC width before you test anything.
Which CRC algorithms does the identifier check?
Every model in the catalog, covering the published CRC-8, CRC-16, and CRC-32 parameter sets including MODBUS, XMODEM, CCITT-FALSE, KERMIT, ISO-HDLC, and CRC-32C. Each match links to its algorithm page, where the full parameter set and check value are documented.