Opening tool…
Runs in your browser. Nothing you enter is uploaded to ALCO.
About this tool.
Work out the SHA-256 checksum of a file — or SHA-1, SHA-384 and SHA-512 — to confirm a download arrived intact or that two copies of a file are byte for byte identical. Paste the checksum the publisher listed and the tool tells you plainly whether it matches, including when the pasted value is a different algorithm from the one selected. Hashing uses your browser’s built-in WebCrypto engine, so the file is read on your own machine and never uploaded, which matters because the files people verify are usually the ones they cannot share.
Using this tool.
Why is there a 32 MB limit?
Browsers cannot hash a file in pieces — WebCrypto has no streaming digest — so the whole file has to be held in memory at once. Above roughly 32 MB that becomes unreliable on a phone or a modest laptop, so the tool refuses clearly instead of freezing. For larger files use shasum on macOS or Linux, or certutil -hashfile on Windows.
Should I use SHA-1?
Only to check against an old published SHA-1 value. Practical collisions have existed since 2017, so a matching SHA-1 no longer proves a file was not tampered with. SHA-256 is the sensible default.
What does it mean when the checksum does not match?
The file you have is not the file that was published. Usually the download was truncated or corrupted, so try again from the original source. If it fails a second time, do not run it.
Where is MD5?
It is not offered here. Browsers do not implement MD5 in WebCrypto, and it has been broken for long enough that adding a library to compute it would mostly encourage its use for the wrong job. If you need to match an old MD5, use the command line.
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