Sign with Certificate
Sign a PDF with your digital certificate, the same kind of signature Adobe Acrobat creates with that file. The certificate, its password and the document stay on your device.
This page has no ads and loads nothing from other websites: only robinpdf's own code handles your certificate, and it never sends it anywhere.
How to sign a PDF with your certificate
- Choose the PDF.
- Choose your certificate file (.p12 or .pfx), type its password and open it.
- Decide whether the signature shows on the page, and where.
- Press "Sign PDF". The signed copy downloads after the signature has been checked.
Is it safe to use my certificate on a website?
Only if the website cannot take it, and you should be able to check that. Here the certificate is opened in your browser and nothing is uploaded: load the page, disconnect from the internet, and it still signs. The page runs no ads or scripts from other sites, the private key is handed to the browser as non-exportable, and the password is not stored. Even so, do not use your certificate on a shared computer.
What signature does it create?
A standard PDF signature (PAdES), the same kind Adobe Acrobat or your national signing app creates with that certificate file. It has no timestamp: adding one would mean contacting a timestamp service, so the signing time is your device's clock.
A PDF that is already signed
Your signature is added at the end of the file without rewriting it, so the earlier signatures stay valid. That is how a contract signed by the other party gets your signature too.
Is it private?
Yes. Everything runs inside your web browser, using your own device. Nothing is uploaded to any server, so your documents stay completely private. On top of that, the tool runs in a private frame, served from a separate address (app.robinpdf.com) and kept apart from the ads: your browser does not let the page around it see the file you open there. How does this work without uploading?
Frequently asked questions
Does it work with an ID card, a USB token or a cloud signature?
No. Those keep the key inside the card, token or server, and a web page cannot reach it. It works with certificates stored as a .p12 or .pfx file.
Where do I get the .p12 file?
Export your certificate from your browser or operating system, including the private key; you choose a password when exporting. Many certification authorities also send it as a .p12 or .pfx file.
How do I check the result?
Open it in Verify PDF Signature or in Adobe Acrobat Reader.