File Checksum Verifier

About this tool

Confirm that downloaded, transferred, or archived files match an expected SHA-256 digest and create manifests for future integrity checks.

File Checksum Verifier hashes exact file bytes with SHA-256, strictly validates portable GNU-style SHA256SUMS text, and records matched, mismatched, unlisted, and unused entries.

• Hashes exact bytes locally with Web Crypto for up to 100 files, 100 MB each, and 500 MB total.
• Strictly validates GNU-style text or binary SHA256SUMS lines and rejects malformed or duplicate filenames atomically.
• Reports matches, mismatches, selected files not listed, and unused manifest entries, then exports a final-newline SHA256SUMS.txt.

How to use Checksum Verifier

Choose up to 100 uniquely named files, optionally paste a SHA256SUMS manifest, resolve every reported manifest error, calculate hashes, review all four result states, and download the final-newline manifest.

When this tool is useful

• After downloading software or large published assets.
• Before and after moving archive files between systems.
• When publishing a checksum manifest for recipients.

Practical tips

• Treat any malformed or duplicate manifest line as a source error; the verifier does not silently ignore it.
• Compare checksums only when the expected digest came through a trusted channel.
• Cancellation takes effect after the browser finishes the file digest already in progress.
• A matching checksum proves byte equality, not that a file is safe.

Examples you can test

Load an example, compare the result with the expected output, then replace it with your own input.

release.zip plus its published SHA-256 value

A green match when the calculated and expected 64-character hashes are identical.

Validation checklist

• Use a trusted expected hash.
• Confirm filenames match manifest entries.
• Investigate every mismatch before using the file.
• Store generated manifests beside the corresponding release or archive.