How to sign a PDF document online: guide 2026

You've received a contract in PDF format and you need to sign it without printing, scanning, or posting? Good news: electronically signing a PDF is today as simple as sending an email, at zero 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 for signing a PDF (and their limitations)

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

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

Method 3: an eIDAS-compliant electronic signature platform (Certyneo, DocuSign, Yousign, etc.). It's 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 editor, 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 on 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 gathered in a single envelope signed at once by the recipient.

Step 3: place the signature fields

Click on the Signature button, then drag the field to where the recipient needs to sign. Repeat for each page that requires an initial (for example, a 10-page contract can have an initial per page plus a final signature). You can also add Date, Text and Checkbox fields for mandatory handwritten entries (read and approved, approved for agreement, 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 OTP SMS: the signer will receive a unique code on their phone before they can validate, 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 in 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 fingerprint that changes with every single byte modified, a certified timestamp (TSA compliant with RFC 3161), and an audit document listing each step. In case of inspection 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 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 go further, consult 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.