File checksum
Work out a file's SHA-256 and check a download arrived intact.
- Runs on your device — the file is never sent anywhere
- No sign-up, no watermarks, no daily quotas
- Free, with no limit on how often you use it
How it works
Publishers list a checksum next to a download so you can prove the file you received is the file they published — not truncated, not corrupted, not tampered with. Verifying it normally means a command line. This does it in a browser tab, and uploading the file to a website to check it would rather defeat the purpose.
How to use it
Hash the file you downloaded and compare the result with the checksum on the publisher's page. They should match exactly, character for character. If they do not, the file is not what the publisher released and should not be trusted.
Which algorithm
SHA-256 is the modern standard and what almost every publisher lists. SHA-512 is stronger still and occasionally used. SHA-1 is included because older projects still publish it, but it is cryptographically broken and should only be used to check against an existing SHA-1 listing, never as your own integrity guarantee.
Why MD5 is not offered
MD5 is thoroughly broken — collisions can be produced deliberately — and browsers do not provide it for that reason. Where a project still lists only an MD5, treat it as a check against accidental corruption rather than against tampering.
Large files
Hashing reads the whole file into memory, so very large files are limited by your device rather than by any rule here. It runs entirely locally, so there is no upload wait whatever the size.
File checksum — questions
What do I compare the result against?
The checksum published on the download page. It should match exactly.
Which algorithm should I use?
SHA-256 unless the publisher lists something else.
Why is MD5 not available?
It is cryptographically broken and browsers do not provide it. Use SHA-256 where you have the choice.
Is my file uploaded?
No. It is hashed in your browser, which is the only sensible way to verify a download.