How to sign a PDF document online: 2026 guide

Have you received a contract in PDF format and you need to sign it without printing, without scanning, without mail? Good news: electronically signing a PDF is now as simple as sending an email, at no cost in the majority of cases. You still have to choose the right method: some popular options (scanned image, Adobe Fill & Sign) have almost no legal value. In this guide, we present to you the real 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 limits)

Method 1: paste 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 identification of the signatory, no guarantee of integrity. In the event of a dispute, the evidence is very weak.

Method 2: Adobe Acrobat Reader (Fill & Sign). Practical for your own handwritten signature captured with the 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.). It is the only method that produces a PDF with cryptographic signature, certified timestamp and full audit trail. Legal value recognized 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 on New envelope, then drag and drop your PDF file (up to 25 MB). The document appears in the editor. You can upload several PDFs in a row: they will be collected in a single envelope signed at once by the recipient.

Step 3: Place the signature boxes

Click 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 may have one initial per page + a final signature). You can also add Date, Text, Checkbox fields for mandatory handwritten information (read and approved, good 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 signatory will receive a unique code on their phone before being able to validate, which reinforces identification and proof value. For a low-stakes document (simple certificate), the SES mode by email click is sufficient.

Step 5: Send and Track

Click Send. The recipient immediately receives an email with a personal link. He clicks, sees the document in full screen, signs in one click (or after entering his OTP). You receive a notification as soon as the signature is complete. The final signed PDF can be downloaded 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

A compliant electronically signed PDF includes several elements: a digital certificate attached to the document (visible via Adobe Reader, Signatures tab), an SHA-256 cryptographic fingerprint which changes at the slightest byte modified, a certified timestamp (TSA compliant with RFC 3161), and an audit document listing each step. In the event of an audit or dispute, these elements constitute your proof — much stronger than an image pasted into Word.

How much does it cost?

For an individual or a small business who signs less than 5 contracts per month, the free plan from Certyneo (or other market players) is more than sufficient: €0 per month, all legal features included. Beyond that, paid plans start 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 signature (/guide/signature-electronique) which details the SES, AES and QES levels, or our article on the legal value compared electronic signature vs handwritten.