🔢 CRC-32 & Adler-32 Checksum Calculator
Type text or drop a file to get its CRC-32 (the ZIP/PNG checksum) and Adler-32 (zlib) values in hex and decimal.
CRC-32 (ZIP/PNG)
414FA339
decimal 1,095,738,169
Adler-32 (zlib)
5BDC0FDA
decimal 1,541,148,634
43 bytes checksummed
CRC-32 and Adler-32 are fast, non-cryptographic checksums used to detect accidental corruption — CRC-32 is the one inside ZIP archives and PNG chunks; Adler-32 is used by zlib. They quickly tell you whether two copies of some data are byte-identical. They are NOT for security or passwords (they're easy to forge on purpose and can collide) — use SHA-256 for that. 🔒 Computed entirely in your browser.
How the crc-32 & adler-32 checksum calculator works
CRC-32 and Adler-32 are fast, non-cryptographic checksums that condense any amount of data into a single 32-bit fingerprint used to detect accidental corruption. CRC-32 (the ISO-HDLC variant) is the exact checksum stored inside ZIP archive entries and PNG chunks, so it is the one to match when validating those formats; Adler-32 is the lighter checksum zlib uses. This tool reads your text as UTF-8 bytes (or reads a file locally), runs both algorithms, and reports each result in uppercase hex and decimal. If two copies of a file produce the same CRC-32, they are byte-identical.
These are integrity checksums, not security hashes: they are excellent at catching random corruption from a bad transfer or disk error, but they are trivial to forge deliberately and different inputs can be made to collide, so never use them to verify authenticity or store passwords — use SHA-256 for that. The standard CRC-32 check value for the ASCII string "123456789" is CBF43926, which you can use to confirm the implementation. Text is hashed as UTF-8, so accented characters count as multiple bytes. Everything runs in your browser; files are never uploaded.
Frequently asked questions
What is a CRC-32 checksum used for?
To detect accidental changes to data. ZIP archives and PNG images store a CRC-32 of their contents so software can confirm nothing got corrupted in transit or on disk. Recomputing the CRC-32 and comparing it to the stored value tells you whether the data is intact.
What is the difference between CRC-32 and Adler-32?
Both are 32-bit integrity checksums, but CRC-32 is a cyclic redundancy check (used by ZIP and PNG) while Adler-32 is a simpler running-sum checksum used by zlib. Adler-32 is a touch faster to compute but slightly weaker at catching short errors; this tool shows both.
Can I use CRC-32 to check a password or for security?
No. CRC-32 and Adler-32 are not cryptographic — they are easy to reverse and to collide on purpose, so they offer no security. Use them only to catch accidental corruption; for passwords or authenticity, use a cryptographic hash like SHA-256.
How do I verify two files are identical?
Compute the CRC-32 of each file and compare. Matching CRC-32 values mean the files are almost certainly identical; for absolute certainty against deliberate tampering, compare a cryptographic hash instead.
What is the CRC-32 of "123456789"?
CBF43926. That is the standard published check value for the CRC-32/ISO-HDLC algorithm, so you can type that string to confirm the calculator matches the reference.
Is my file uploaded to compute the checksum?
No — the file is read and checksummed entirely in your browser, so nothing leaves your device and it works offline.