Free tool · runs on your device
Checksum checker for downloaded software
Free SHA-256 checksum checker that runs in your browser. Drop a downloaded installer, paste the publisher's hash and see if they match. The file is never uploaded.
Check a file
Drop the installer here
or
The file stays on your device. Nothing is uploaded.
Result
Choose a file to see its SHA-256 checksum.
How to
Verify a download in four steps
- 1
Find the checksum on the publisher's download page (often labelled SHA-256, SHA256SUMS or checksum).
- 2
Drop the file you downloaded into the checker above, or choose it.
- 3
Paste the publisher's checksum into the box.
- 4
A match means your file is byte-for-byte the one they published. A mismatch means download it again from the official site.
No browser needed
Check a hash from the command line
Windows (PowerShell)
Get-FileHash .\installer.exe -Algorithm SHA256Mac (Terminal)
shasum -a 256 ~/Downloads/installer.dmgLinux (Terminal)
sha256sum ~/Downloads/installer.AppImage
FAQ
Checksum questions
Is my file uploaded anywhere?
No. The checker reads the file with your browser's File API and hashes it with the built-in WebCrypto library on your device. Nothing is sent to AltFTool or anyone else.
What does a checksum prove?
That the file you have is identical to the file the publisher hashed. It catches corrupted and tampered downloads. It only helps if you got the checksum from the publisher's real site, so take it from the official page, not from a mirror.
Which algorithm should I use?
Use whatever the publisher lists, which is usually SHA-256. SHA-512 is also common. SHA-1 and MD5 are outdated and should only be used when nothing else is offered.
Is a checksum the same as a digital signature?
No. A signature proves who made the file. Windows shows the verified publisher in the User Account Control prompt, and macOS checks notarisation through Gatekeeper. A checksum proves the file is unchanged. Using both is best.
Why does it fail on very large files?
Browsers keep the file in memory while hashing, so files over 2 GB are refused. Use the one-line terminal commands on this page instead.