PDF electronic signature: sign a PDF online in 30 seconds
Do you have a PDF to get signed (quote, contract, mandate, confidentiality agreement)? Certyneo allows you to sign a PDF online without installing Acrobat, without printing-scanning, and without compromising file integrity. The electronic signature applied is eIDAS compliant, the PDF remains readable on any PDF/A compatible reader, and each signature generates a timestamped audit trail admissible in court.
Comparison of PDF signature solutions in 2026
| Solution | PDF Format | eIDAS Compliance | Free plan | Hosting |
|---|---|---|---|---|
| Certyneo | PDF/A preserved + visual seal | SES + AES | 5 PDFs/month, permanent | EU |
| Adobe Acrobat Sign | Native Adobe PDF | SES + AES + QES | 7-day trial | US (Adobe Cloud) |
| Smallpdf | Reformatted PDF | SES only | 2 PDFs/day only | Switzerland |
| iLovePDF | Image pasted in PDF | Non-eIDAS | Limited, with watermark | Spain |
| DocuSign | Reformatted PDF | SES + AES | 30-day trial | Global / EU option |
Why sign your PDFs with Certyneo
Certyneo is designed to preserve the integrity of your PDFs: no reformatting, no destructive compression, no watermark. The original file is encapsulated in a digitally signed PDF/A, accompanied by a signature certificate and an audit trail. Cryptographic proof allows you to verify that no pages have been added or modified after signing.
- PDF/A long-term (10-year archiving)
- Fonts and images preserved
- Visible signature + cryptographic signature
- Qualified timestamped audit trail
- Compatible with Acrobat Reader, macOS Preview, Foxit
- Multi-signers in parallel or in sequence
- Integrity verification in one click
How to sign a PDF online in 3 minutes
- 1
Import your PDF
Drag and drop the file into Certyneo. Size up to 50 MB, up to 200 pages.
- 2
Place the signature fields
Click where each signer should sign. Add date, initials or checkbox if needed.
- 3
Indicate the signers
Email is enough. You can set a signing order or let everyone sign in parallel.
- 4
Send the signature request
Each signer receives a secure email link, valid for 30 days. No account required to sign.
- 5
Retrieve the signed PDF
Timestamped PDF/A + signature certificate + audit trail downloadable as soon as everyone has signed.
What PDF formats does Certyneo accept?
All standard PDFs (PDF 1.4 to PDF 2.0), including interactive PDF forms with AcroForm fields. PDF/A-1, PDF/A-2 and PDF/A-3 are preserved as is. If your PDF is a scanned image, Certyneo accepts it too but we recommend OCR beforehand to preserve text selection. Password-protected PDFs must be unlocked before import.
Three ways to sign a PDF: which one to choose?
Not all “PDF signatures” are equal in the eyes of the law. Three approaches coexist:
The pasted signature image
Scanning or drawing your signature and inserting it into the PDF only creates an image, with no cryptographic link to the document: easy to copy, impossible to verify, and of almost no evidential value in a dispute.
The local certificate (PDF reader, smart card)
Signing with a certificate installed on your machine produces a real digital signature, but means buying and renewing a certificate — and the recipient must do the same to countersign.
The online signing platform
The document is signed in the browser: signer authentication (email, OTP code), PAdES sealing, timestamping and audit trail, with no certificate to buy and no software to install. It is the simplest eIDAS-compliant way to sign a PDF with several parties.
Signed PDF: how to verify the signature?
Open the PDF in a compatible reader (the “Signatures” panel shows the document's integrity and the certificate's validity). You can also use our free tool: verify a signed document →
Frequently asked questions about PDF electronic signature
- Does an electronic signature on a PDF have the same legal value as a handwritten signature?
- Yes, provided the solution complies with eIDAS. Certyneo generates SES (simple) and AES (advanced) signatures compliant with Regulation (EU) 910/2014, which have the same probative value as a handwritten signature before a European court.
- Will my signed PDF remain readable by Acrobat Reader?
- Yes. The signed PDF remains a standard PDF that can be opened in Acrobat Reader, Preview (macOS), Foxit, or any PDF/A-compatible reader. Acrobat Reader additionally displays a validation bar indicating that the signature is cryptographically valid.
- How to verify that a signed PDF has not been modified after signature?
- The signed PDF contains a cryptographic seal calculated over the entire file at the time of signature. Any subsequent modification (even a single comma changed) breaks the seal and triggers a warning in Acrobat Reader. Certyneo also provides an online verification tool.
- Can you sign a PDF for free without installing software?
- Yes. Certyneo works entirely in the browser, with no installation. The free plan covers 5 PDFs per month, with no expiration and no credit card required.
- Can a PDF be signed by multiple people?
- Yes. You can add as many signatories as needed, define a sequential order (signatory A then signatory B) or let everyone sign in parallel. Each signature generates its own proof of identity in the common audit trail.
- How can I sign a PDF for free?
- Create a free account: the Free plan lets you sign and send PDFs for signature without a credit card. The simple signature suits everyday documents; paid plans add the advanced signature with SMS OTP and higher volumes.
- How do I sign a PDF on mobile?
- Open the signing link received by email on your smartphone: the document opens in the browser and you sign with your finger or in one tap, with no app to install. iOS and Android are supported.
- Can several people sign the same PDF?
- Yes: add as many signers as needed, in parallel or in a set order. Each one receives an invitation, signs in turn, and the final PDF consolidates all the signatures with a single audit trail.
- Is signing a PDF online legal?
- Yes: the eIDAS regulation recognises the electronic signature of a PDF as long as the process identifies the signer and guarantees the document's integrity. PAdES sealing and the audit trail provide exactly those guarantees.