XSealSeal a document. Prove it never changed.
Upload any file and XSeal returns a cryptographically signed certificate with a timestamped SHA-256 hash. Later, anyone can prove the file is byte-for-byte identical to what you sealed — or that it was tampered with. Built for Dutch & EU businesses.
Free to try. Sign up to keep a record of every seal in your dashboard. XSeal stores only the hash + metadata — never your file contents.
Why teams seal documents with XSeal
Tamper-evidence
Any change to a sealed file — even a single byte — breaks the hash, so alteration is provable, not a matter of opinion.
Trusted timestamp
Each seal records the exact UTC moment it was created, establishing that the document existed in that form at that time.
Privacy by design
XSeal hashes your file in your session and stores only the SHA-256 digest and metadata. Your file contents never leave your hands.
Built for the EU
Operated for Dutch & EU businesses with billing and VAT handled by Website Holding as merchant of record.
How it works
- Choose a file. XSeal computes its SHA-256 hash — the file itself is never uploaded.
- XSeal signs the hash with its service key and records a UTC timestamp, returning a Seal ID.
- Keep the certificate. Logged-in users get every seal saved automatically in their dashboard.
- Verify any time: re-upload the file with its Seal ID and XSeal confirms it is authentic or altered.
Simple, honest pricing
Start free with unlimited verification. Upgrade to Pro for higher seal volumes, longer retention, and an API for your own systems.
Frequently asked questions
Does XSeal store my file?
No. XSeal computes the SHA-256 hash and stores only that digest plus metadata (filename, size, timestamp). The file contents are never transmitted or kept.
What does a seal prove?
That a specific file existed in an exact byte-for-byte form at the sealed timestamp. If anyone later changes the file, verification fails — that is the tamper-evidence.
Can I verify without an account?
Yes. Verification is free and open to anyone with the file and its Seal ID — an account is only needed to keep a saved history of the seals you create.
Is a hash-sealed document legally valid in the EU?
A seal is strong tamper-evidence: it proves a file is byte-for-byte identical to what existed at the sealed UTC timestamp. Under the EU eIDAS regulation electronic evidence like this is admissible and supports a document's integrity — a seal proves integrity and timing rather than signer identity.
How is XSeal different from an electronic signature?
An e-signature proves who signed a document and that they intended to; an XSeal proves a file's contents are unchanged since a specific moment. They are complementary — sign to establish identity and intent, seal to prove the exact bytes were never altered afterwards.