File Checksum Calculator (MD5, SHA256)
Verify a download, and work out which algorithm made the checksum. Free, and runs entirely in your browser — nothing you enter is uploaded or stored.
About File Checksum
Reads a file's bytes and computes SHA-1, SHA-256 and SHA-512 digests with Web Crypto. Paste the checksum a project published and it is compared for you, so verifying a download is a single step rather than a manual character-by-character read.
This is the check that catches a truncated download or a corrupted transfer, and — when the published checksum comes from a trustworthy source over a channel an attacker does not control — a tampered file.
Show every algorithm answers the other question: which one made the checksum you were given? A release page prints sixty-four hex characters and frequently does not say whether they are SHA-256, SHA3-256, BLAKE2s or BLAKE3, and the only way to find out is to try. It hashes the file with all fifteen and names the one that matched. It is off by default and limited to small files because it is genuinely expensive — the set runs at roughly eight hundred milliseconds per megabyte, most of it the SHA-3 family, and unlike the three above it runs in the page rather than in the browser's own implementation.
Where it helps
- Identifies which algorithm a published checksum came from, instead of leaving you to guess.
- Three algorithms at once, so whichever the project published is covered.
- Automatic comparison against an expected value removes human error.
- The file is read locally; nothing is uploaded regardless of size.
- Works on any file type, including large archives and disk images.
Limits
- A checksum only proves the file matches that value — trust depends on where the value came from.
- A checksum published on the same page as a compromised download proves nothing.
- SHA-1 is offered for compatibility with older projects and is not collision resistant.
- Very large files take time to read, and the tab is busy while they do.
Frequently asked questions
The checksum does not match. What now?
Download again — truncation is the usual cause. If it still differs, do not run the file and check whether the project rotated its release.
Which algorithm should I compare?
Whichever the publisher listed. SHA-256 is the modern default; SHA-1 appears on older projects and is weaker.
Does a matching checksum mean the file is safe?
It means the bytes match what was published. If the publisher's page was compromised, both the file and the checksum could be the attacker's — signatures are the stronger check.
Is my file uploaded?
No. It is read from disk into this tab and hashed by the browser.
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