Seal · in your browser

Create a seal

A seal proves the data is unaltered and matches the seal. It does not make the contents true. Everything happens in your browser with a fresh key that is discarded after sealing; we never see your key or your data.

Choose a file (hashed in your browser, never uploaded)

Title (optional, included in the signed seal)

Include my timezone as a claimed, unverified value. Anything you mark claimed is embedded in the bundle and visible to anyone you share it with. The tool cannot confirm it is true.

Private fields (optional)

A private field commits to a value without putting it in the bundle in the clear. The commitment is sealed; the value is encrypted (or, for proof-only, not stored at all). Concealment strength equals your password strength.

Press and hold (or focus and hold Space/Enter) for 2.5s to seal. The time syncs during the hold.

Verifying cryptography in your browser…