How to sign a PDF online
“How do I sign a PDF” has three different answers depending on the situation you are in. Before hunting for a tool, it pays to work out whether you are signing somebody else’s finished document or one that is still being created — and whether anyone is going to demand a qualified signature.
Three situations, three answers
You have a finished PDF from someone else
You need a tool that inserts a signature into an existing file. Preview on macOS, Acrobat Reader and most mobile PDF viewers will do it. Gatherino will not — it cannot sign an uploaded file.
The document is still being created
Here signing a finished PDF is a needless detour. If the other party fills in the fields in a form and signs there, the PDF is generated already signed and nobody exports or uploads anything.
Somebody wants a qualified signature
Where the law requires it, a finger signature is not enough. You need a qualified certificate from an accredited provider. That is not a job for a form tool.
How the signature levels differ
eIDAS distinguishes three levels. A <strong>simple electronic signature</strong> is anything electronic expressing the will to sign — including one drawn with a finger. Under Article 25(1) it may not be denied legal effect merely for being electronic.
An <strong>advanced signature</strong> must be uniquely linked to the signer and make later changes to the document detectable. A <strong>qualified signature</strong> is an advanced signature based on a qualified certificate; in the EU it has the same effect as a handwritten one.
For ordinary commercial contracts, consents, handover protocols or orders, the simple signature is what gets used in practice. You need a qualified one where the law explicitly asks for it — and that is worth checking, because a general answer will not do here.
When the document is still being created
- 1
Turn the document into a form
Instead of a Word template, build a form with the fields that get filled in anyway. The rest of the text stays as the fixed part of the document.
- 2
Add a signature field
The respondent signs with a finger on a phone or a mouse on a desktop. The alternative is typing the name, which is rendered in a handwriting-like font.
- 3
Turn on the PDF attachment
After submission a PDF with the filled details and the signature is generated and emailed to both sides.
- 4
Keep the audit trail
The submission time, IP address and browser are stored with the signature. That is evidence of the circumstances, not of identity.
What this does not solve
A simple electronic signature does not verify who made it. Gatherino does not establish the signer’s identity — it records what was signed, when, from which IP address and in which browser. For higher-value deals, verify the other party outside the form too; for acts with a prescribed form, ask a lawyer.
FAQ
Is a finger signature legally valid?
It is a simple electronic signature under eIDAS and is used for ordinary contracts and consents. It is not suitable for acts requiring a qualified signature.
Can Gatherino sign a PDF I upload?
No. Gatherino generates a signed PDF from a form response, but it cannot sign a finished uploaded file.
Can I sign on a phone?
Yes — signing with a finger on a touchscreen works the same as with a mouse. Tablets are the most comfortable.
What is stored with the signature?
The signature image, submission time, IP address and the respondent’s browser. It serves as an audit trail.
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