Seal documents without uploading them

XSeal now lets you seal documents without uploading them. When you seal or verify a file on the website, your browser computes its SHA-256 fingerprint and sends only that, with the file name and size. The contents of the file never leave your device.

Nothing changes in what a seal proves. The certificate still binds the fingerprint to a UTC timestamp with XSeal's Ed25519 signature, and anyone who has the same file can verify it against the seal. Because a fingerprint reveals nothing about the contents, confidential contracts and personal documents can be sealed without sending them anywhere.

Verification works the same way: the recipient chooses their copy of the file, their browser computes the fingerprint, and XSeal reports whether it matches the sealed version.

Bulk sealing and sealing a new version from the dashboard still send the file over an encrypted connection, where it is hashed in memory and discarded. XSeal never stores file contents. Try it at xseal.nl.