Checksum Calculator

How to use it

1. Paste or type text into the input panel, or choose a local file instead.
2. Click Calculate to get all three checksums at once; typing already updates them live.
3. Each result shows eight uppercase hex digits in the field and the unsigned decimal value beneath it.
4. Use Copy under any single value to take just that checksum.
5. Switch sources by clearing the file input and editing the text, or pick a new file to replace it.

Common use cases

• Verifying a download - compare the CRC-32 of a file against the value published alongside it.
• Debugging a protocol or storage format - CRC-32 and Adler-32 are what many container formats embed in their trailers.
• Building a hash table or bloom filter - FNV-1a 32 is a small, fast mixing function for buckets.
• Spotting truncated transfers - a checksum that matches the sender means the bytes arrived intact.
• Checking generated output - feed the same text through two builds and compare the values.

Why it stays private

Text and files are read straight into browser memory with the FileReader API and never sent anywhere. Documents you have not published, customer exports and internal archives stay on your device.

FAQ

Q: What is the difference between these checksums and the hash tool's MD5 or SHA values? A: These three are non-cryptographic checksums. They are designed to catch accidental corruption such as a bad sector or a truncated transfer, and they are far too easy to collide on purpose. MD5 and the SHA family belong to the hash tool and have much stronger collision behaviour, though for security decisions you should use SHA-256 or better rather than MD5.

Q: Why do I get three different values for the same text? A: They are different algorithms. CRC-32 is a polynomial remainder, Adler-32 sums positions with a modulus, and FNV-1a multiplies and xors on every byte. Each one is compared only against a value produced by the same algorithm.

Q: Can I use one of these to store passwords or sign data? A: No. None of them is suitable for passwords, signatures or any integrity guarantee against an attacker. Their 32-bit output also makes deliberate collisions trivial to construct. Use a real cryptographic hash for that job.

Q: Why does the file result change when I pick a different file? A: The file's raw bytes are the input, so two files with the same visible content but different encoding or metadata produce different checksums. That is the point: the checksum covers every byte.