SECURITY
File Hash Checker
Calculate MD5, SHA-1, SHA-256, or SHA-512 checksums locally.
LOCAL CHECKSUMS
Hash a local file
Hashing…
Your file stays on this device and is never sent to NAB Tools.
File hash calculator guide
A file hash is a fingerprint: a fixed-length string that changes completely if even one byte of the file changes. That makes it the standard way to verify downloads, detect corruption, and check that a file is exactly what its publisher published.
This tool computes MD5, SHA-1, SHA-256, and SHA-512 checksums of any local file — entirely in your browser. Files are read locally and never uploaded.
Verifying a download
Software publishers publish a checksum (usually SHA-256) on their download page. The workflow: download the file, compute its hash here, and compare the two strings. If they match, the file is byte-for-byte identical to what the publisher shipped — no corruption, no tampering in transit.
Always prefer SHA-256 or SHA-512 for this. MD5 and SHA-1 are broken against deliberate tampering — an attacker can craft a different file with the same MD5 — so they are only safe for detecting accidental corruption.
Which algorithm when?
- SHA-256 — the modern standard for download verification, certificates, and Git.
- SHA-512 — a longer variant; used when a 512-bit output is needed.
- MD5 — legacy; still seen in old systems and as a fast cache key, but cryptographically broken.
- SHA-1 — deprecated since 2017 (real collisions demonstrated); avoid for security.
Why hashing works
A cryptographic hash is a one-way function: it is trivial to compute, but infeasible to reverse or to find two different inputs with the same output (for secure algorithms). Even changing one character of a multi-gigabyte file produces a completely different hash — which is why a mismatch is definitive proof something changed.
This tool hashes the file in memory via the Web Crypto API (with a local MD5 implementation for compatibility), so it works on files of any size your device can handle — no server involved at any step.
Frequently asked questions
What is a file checksum?
A hash of a file’s entire contents — a fixed-length string that changes if any byte changes. Used to verify downloads and detect corruption or tampering.
How do I verify a downloaded file?
Compute its SHA-256 here and compare with the checksum on the publisher’s site. Identical strings = identical files.
Is MD5 safe to use?
No, not against deliberate tampering — MD5 collisions can be crafted in seconds. It is fine for accidental-corruption checks but never for security verification.
Are large files supported?
Yes — hashing happens in your browser’s memory via Web Crypto, so any file your device can open works. Very large files may take a moment.
Is my file uploaded?
Never. Files are read locally and hashed in your browser — nothing is transmitted.
Privacy note: file hashing happens in your browser. Your file is not stored or uploaded.