🔍 Document Verification
Verify Any File
Check if a file has been sealed on Attestum. Your file never leaves your device — only the cryptographic fingerprint is checked.
Drop any file here to seal it
or click to browse · any file type · max 100 MB
HOW IT WORKS
How file verification works
Select any file
Drag and drop or click to browse. Works with any file type. Your file is never uploaded — it stays entirely on your device.
Fingerprint computed locally
The Web Crypto API computes a SHA-256 hash entirely in your browser. This 64-character fingerprint is mathematically unique to your file's exact contents.
Checked against all seals
Only the fingerprint is sent to our server and compared to every attestation on Attestum. If a match exists, you'll see who sealed it and when.
TRUST LEVELS
What a verification result tells you
Integrity
This file's content has been verified — it existed in this exact form at the stated time. The timestamp and fingerprint are sealed on the blockchain.
Authorship
A verified person sealed this file — you know who created or endorsed it. Identity is bound to the blockchain record.
Seal your first file for free
3 free seals every month. No credit card required. Your file never leaves your device.