Digital Sign PDF
Add a visual "digitally signed" block with signer name, reason, date, and a SHA-256 integrity fingerprint. Not a legally-binding PKI signature — see the FAQ. Free, private, browser-based.
Click to select a PDF file, or drag and drop
Your file never leaves your browserPlace signature block on
How to Digitally Sign a PDF
- Upload the PDF you want to sign.
- Enter your name and, optionally, a reason for signing.
- Choose whether to place the signature block on the first or last page.
- Click Add Signature Block to download the signed PDF.
What this tool actually does
A real, standards-based digital signature (PAdES, eIDAS-qualified, or similar) requires an X.509 certificate issued by a trusted certificate authority and a chain of trust that a browser-only, backend-free tool cannot provide. Instead, this tool stamps a visible signature block onto your PDF containing the signer's name, reason, the signing date, and a SHA-256 hash computed from the original file's bytes. That hash is a genuine cryptographic fingerprint — if even one byte of the original file changes, the hash changes completely — so it can serve as an integrity reference, but it does not prove who added it or provide legal non-repudiation the way a PKI-based signature does.
Example
A freelancer sends a signed-off scope-of-work PDF to a client. Adding a signature block with their name, the reason "Approved scope of work", and a hash reference gives the client a visible confirmation and a way to verify the file hasn't been altered since — useful for informal approval trails, though not a substitute for a legally binding e-signature service on contracts that require one.
Common Use Cases
- Adding a visible sign-off marker to internal documents, drafts, or approvals.
- Attaching an integrity fingerprint so recipients can confirm a file wasn't modified after signing.
- Quick, informal "signed by" stamps where a full e-signature platform is overkill.
FAQ
- Is this a legally-binding electronic signature? No. It does not meet PAdES, eIDAS, or similar legal digital-signature standards, which require a certificate from a trusted authority. For contracts, legal filings, or anything requiring a legally recognized signature, use a dedicated e-signature service (such as DocuSign or Adobe Sign) instead.
- What is the SHA-256 hash for? It's a fingerprint of the original file's exact bytes, computed in your browser before signing. Anyone can independently hash the original file and compare it to confirm it matches — but this only proves the file's integrity, not the signer's identity or intent.
- Can this be forged? Yes — because there's no certificate authority validating identity, anyone could type any name into the signer field. Treat this as a visible annotation and integrity marker, not proof of authenticity.
- Is my file uploaded anywhere? No — hashing and signing both happen entirely in your browser.