📄 Document Verification

Seal Any File on the Blockchain

Your file never leaves your device. Only the cryptographic fingerprint is stored — permanently and tamper-proof.

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: PDFs, images, code, ZIP archives, videos. Your file is never uploaded — it stays on your device.

Fingerprint in your browser

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.

Sealed on Base blockchain

Only the fingerprint is sent to our server and recorded on Base blockchain via EAS. The timestamp and hash are permanently immutable and publicly verifiable.

Your file never uploads. Never.

The cryptographic fingerprint is computed entirely in your browser using the Web Crypto API. Attestum™ never sees, stores, or transmits your file. Only the 64-character fingerprint is sent to our server and sealed on the blockchain.