How do I sign a PDF electronically for free?

Open OptaPDF Sign PDF, upload your document, then type your name in a signature font, draw your signature with a mouse or finger, or upload an image of your signature. Place it on the page and download — free, no account.

Is an electronic signature legally valid?

In most countries, electronic signatures are legally recognized for the majority of everyday agreements under laws such as the ESIGN Act and eIDAS. For high-stakes legal documents, check the specific requirements that apply to you.

Can I sign a PDF on my phone?

Yes. OptaPDF works in mobile browsers, and the draw option supports touch, so you can sign with your finger on a phone or tablet.

How do I protect a signed PDF from changes?

After signing, use Protect PDF to add a password, or flatten the document so the signature cannot be easily moved.

PDF Editing

How to Sign a PDF Electronically on Any Device (2026)

By The OptaPDF Team • Published June 19, 2026 • 5 min read

Printing a document just to sign it and scan it back is a waste of time. You can add an electronic signature to a PDF in under a minute, on any device, for free. Here is how — plus a note on whether e-signatures are legally valid.

Three ways to sign

Open Sign PDF, upload your document, and choose the method that suits you:

Type it. Enter your name and pick a handwriting-style font. Fast and clean for everyday agreements.
Draw it. Sign with your mouse, trackpad, or — on a phone or tablet — your finger or a stylus. The most natural-looking option.
Upload it. Have a photo or scan of your signature? Upload the image and place it on the page.

Then position the signature where it belongs, resize it, and download your signed PDF.

Signing on a phone

Because OptaPDF runs in your mobile browser, signing on the go is easy: open the tool, upload (or pick from your files), draw your signature with your finger, and download. No app to install.

Are electronic signatures legal?

For most everyday agreements, yes. Electronic signatures are broadly recognized under laws such as the ESIGN Act in the US and eIDAS in the EU. That said, certain documents (some wills, property deeds, and notarized items) may have stricter requirements. For high-value or legally sensitive contracts, confirm what applies in your jurisdiction.

Protect your signed document

Once signed, you may want to prevent tampering. Add a password with Protect PDF so only intended recipients can open it, or keep a clean copy for your records. If you are dealing with fillable forms, PDF Forms can help you complete fields before signing.

Privacy

Signed documents are often sensitive. OptaPDF encrypts your file in transit, never reviews it manually, and permanently deletes it within 30 minutes. See our Security Policy for details.

Summary

Type, draw, or upload — whichever you choose, signing a PDF is quick and free with Sign PDF. Add a password afterward if the document needs protecting, and you are done without ever touching a printer.