Verify a document fingerprint

Every PDF or Word file that SealForms generates with at least one signature ends with a signature certificate: who signed, when, and a document fingerprint (a SHA-256 hash of the text). Paste the document text below to recompute the fingerprint and compare it with the one on the certificate. Everything runs in your browser — nothing is uploaded.

What the fingerprint proves — and what it doesn’t

A SHA-256 fingerprint is a 64-character code derived from the exact text of the document. Change a single character — a price, a date, a name — and the code changes completely. So if the fingerprint you compute here matches the one on the certificate, the text you have is the same text that existed when that PDF was generated.

• It proves integrity of the text. The wording, figures and typed signatures have not been altered since the certificate was produced.
• It does not prove identity. It cannot tell you who typed or drew a signature, or that the timestamp on the certificate is accurate — those come from the signer’s own device, with no third party checking them.
• It is not a qualified or certified electronic signature. SealForms does not verify identities, keep audit logs, or hold copies of your documents. Whether a simple electronic signature is valid for your document depends on your jurisdiction and the type of document — some (wills, certain deeds) need wet ink, witnesses or a notary.
• Keep your own copy. Because nothing is stored on our servers, the PDF each party keeps is the only record. Compare fingerprints between copies if there is ever a dispute about the wording.

How the fingerprint is computed

Take the text of the document (everything before the certificate page, typed signatures included), collapse every run of whitespace to a single space and trim the ends. If there are drawn signatures, append the SHA-256 of each signature image (the “Image hash” lines on the certificate), separated by single spaces. Hash the result with SHA-256 and write it as lowercase hex. This page does exactly that using your browser’s built-incrypto.subtle, so you can also reproduce it with any standard tool.

Text copied out of a PDF can occasionally pick up stray characters (ligatures, hyphenation, hidden headers). If a fingerprint doesn’t match, first try copying the text again or from the Word (.docx) version, then compare the wording by eye before concluding the document was changed.

Looking for a template? Browse all US documents — free, no signup, signatures included.