How to Sign a PDF Document Online: Guide 2026

You've received a contract in PDF format and need to sign it without printing, scanning, or posting? Good news: electronically signing a PDF is now as simple as sending an email, at no cost in most cases. You just need to choose the right method: some popular options (scanned image, Adobe Fill & Sign) have virtually no legal value. In this guide, we present you with genuine eIDAS-compliant solutions, their limitations, and how to sign your first PDF in two minutes flat.

The 3 Methods to Sign a PDF (and Their Limitations)

Method 1: pasting a scanned signature image. This is the most common but least secure solution. Legally, this does not constitute an electronic signature within the meaning of Article 1367 of the Civil Code: no signer identification, no integrity guarantee. In case of dispute, the evidence is very weak.

Method 2: Adobe Acrobat Reader (Fill & Sign). Practical for capturing your own handwritten signature with a mouse, but again: no digital certificate, no timestamp, no audit trail. Legal value almost identical to the scanned image.

Method 3: an eIDAS-compliant electronic signature platform (Certyneo, DocuSign, Yousign, etc.). This is the only method that produces a PDF with cryptographic signature, certified timestamp and complete audit trail. Legal value recognised throughout Europe.

Step 1: Choose Your Platform

Most platforms offer a free plan sufficient for a few signatures per month. For this guide, we use Certyneo (free plan: 5 envelopes/month, French publisher, servers hosted in France, GDPR compliant). Create your account at certyneo.com/signup — no credit card required, email verification in 30 seconds.

Step 2: Upload Your PDF

From your dashboard, click New Envelope, then drag and drop your PDF file (up to 25 MB). The document appears in the editor. You can upload multiple PDFs in succession: they will be grouped into a single envelope signed at once by the recipient.

Step 3: Place the Signature Fields

Click the Signature button, then drag the field to where the recipient should sign. Repeat for each page that requires a signature (for example, a 10-page contract might have one signature per page plus a final signature). You can also add Date, Text, and Checkbox fields for mandatory handwritten notes (read and approved, approved, etc.).

Step 4: Add the Signer

Enter the name and email of the person who needs to sign. For a high-stakes contract (employment contract, lease, important NDA), activate AES mode with SMS OTP: the signer will receive a unique code on their phone before they can confirm, which strengthens identification and proof value. For a low-stakes document (simple certificate), SES mode by email click is sufficient.

Step 5: Send and Track

Click Send. The recipient immediately receives an email with a personal link. They click, see the document full screen, sign with one click (or after entering their OTP). You receive a notification as soon as the signature is complete. The final signed PDF is downloadable from your dashboard, accompanied by an audit certificate (separate PDF) which timestamps each action: document opening, OTP validation, signature, IP address, user agent.

What a Compliant Signed PDF Contains

An electronically signed PDF that is compliant includes several elements: a digital certificate attached to the document (visible via Adobe Reader, Signatures tab), a SHA-256 cryptographic hash that changes at the slightest byte modification, a certified timestamp (TSA compliant with RFC 3161), and an audit document listing each step. In case of review or dispute, these elements constitute your evidence — far more solid than an image pasted into Word.

How Much Does It Cost?

For an individual or small business signing fewer than 5 contracts per month, Certyneo's free plan (or other market players) is more than sufficient: €0 per month, all legal features included. Beyond that, paid plans start at around €10/month for intensive use (50 to 200 envelopes). See the /pricing page for details of Certyneo's plans.

Ready to Sign Your First PDF?

Create your free account at certyneo.com/signup and send your first envelope in less than 3 minutes. To learn more, see our pillar guide on electronic signatures (/guide/signature-electronique) which details SES, AES and QES levels, or our article on the comparative legal value of electronic vs handwritten signatures.