Sign a PDF online for free without installing software

How do I sign a PDF with an electronic signature, for free and without installing software? With firmar.ec: open app.firmar.ec in your browser, load the PDF and your .p12 certificate, and enter the password. You download the document with a PAdES signature valid before the SRI and other Ecuadorian institutions. It is free, open source (AGPL-3.0), with no sign-up, no account and nothing to install — no desktop software, no Java, no token driver. The signature is computed inside your browser: the document is never uploaded to a server.

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What you need (and what you don’t)

The PDF you want to sign.
A valid electronic signature certificate as a .p12 (or .pfx) file, issued by an ARCOTEL-accredited Ecuadorian ECI (BCE, Security Data, Uanataca, Consejo de la Judicatura, ArgosData and more). If you don’t have one, see how to get a certificate.

You do not need to install software, create an account, register an email, or pay. It works in any modern browser on desktop or mobile — for the phone walkthrough see signing from your phone.

Step by step (2 minutes)

Open app.firmar.ec/sign in your browser.
Load the PDF — drag it in or pick it.
Load your .p12 certificate and enter the password. The app checks it comes from an ARCOTEL-accredited Ecuadorian ECI; the key is processed on your device only.
Place the visible stamp (optional) with your name, issuing CA, date and a verification QR.
Sign and download. The result is a PAdES signature (ETSI EN 319 142), the same profile MINTEL’s FirmaEC produces.

Free for real: where’s the catch (there isn’t one)

firmar.ec is free software under AGPL-3.0, with the code published on GitHub, operated by IDK Manager and sustained by sponsorships. There is no paid plan unlocking the signature: signing and verifying PDFs is free. The only thing that costs money is the certificate, and you pay that to the issuing ECI, not to firmar.ec — reference prices are in pricing.

”Free online signing” doesn’t always mean an electronic signature

Most global PDF tools answering “sign PDF online free” insert an image of your handwritten signature or a simple signature. That works for many purposes, but it is not an Ecuadorian advanced electronic signature: it does not use your .p12 certificate from an ARCOTEL-accredited ECI, so it lacks the handwritten-signature equivalence granted by art. 14 of Ecuador’s Electronic Commerce Law (Law 2002-67). firmar.ec signs with your certificate, produces the PAdES Baseline profile, and the result validates in FirmaEC, Adobe Reader and the SRI validator. Full comparison: firmar.ec vs Adobe Sign.

Honest limits

PDFs only in this version: XAdES (SRI XML) and CAdES are not in v1.
Up to 50 MB per PDF (40 MB per file in batch signing).
No physical USB token support: signing uses .p12 / .pfx files. For tokens, use FirmaEC — see the comparison.

Frequently asked questions

Is signing a PDF on firmar.ec really free? Yes. Signing and verifying PDFs is free, with no sign-up and no paid plan: the project is open source (AGPL-3.0) and sponsor-funded. The only cost is the electronic signature certificate, charged by the issuing ECI, not by firmar.ec.

Do I have to install anything or create an account? No. It is a web app: no desktop software, no Java, no token driver, and no account. Open the app in your browser, sign, download.

Is the signature legally valid in Ecuador? Yes. Signed with a certificate from an ARCOTEL-accredited ECI it is an advanced electronic signature under Law 2002-67, with the same legal effect as a handwritten signature (art. 14). The resulting PDF validates in FirmaEC, Adobe Reader and the SRI validator.

Is my document uploaded to a server? No. The signature is computed inside your browser with the Web Crypto API: neither the PDF nor your private key leaves the device. See sign a PDF without uploading it to a server.