Hash. Prove.
Never upload.
Drop any file to compute its SHA-256 fingerprint in your browser — the same math behind docstoc's free tamper-evident certificates.
Click or drag a file here
Get a free tamper-evident fingerprint
SHA-256 · computed in your browser · nothing ever uploaded
No credit card required · your account in one click
What this proves
Hash the same file twice — even on different computers — and you get the exact same result. Change a single character and the hash changes completely. That's how you confirm a file wasn't altered after you last checked it.
Turn this into a shareable certificate →
FAQs
Is my file uploaded anywhere?
No. The hash is computed entirely in your browser using the Web Crypto API — the file's bytes never leave your device or get sent to any server.
What is SHA-256 used for?
SHA-256 produces a fixed-length fingerprint of a file. If even one byte changes, the hash changes completely — making it a reliable way to prove a file hasn't been altered.
How is this different from a docstoc certificate?
This tool just shows you the hash. A docstoc certificate stores that hash with a timestamp and gives you a shareable link anyone can use to verify the file later — this calculator is the same math, without the record-keeping.