How to sign a PDF electronically

"Sign a PDF" covers three different jobs. You received a form and just need to add your own signature. You created a document and need to sign it yourself before filing it. Or you need someone else — a client, a tenant, a contractor — to sign it, which means you need a way to send it and get it back signed. The right tool for the first two is not always the right tool for the third.

If the only requirement is your own mark on your own copy, the free tools already on your computer are usually enough.

• Mac: open the PDF in Preview, click the markup toolbar icon, and use the signature tool. It lets you draw with the trackpad or sign on paper and photograph it with the camera once.
• Windows: Adobe Acrobat Reader has a free Fill & Sign tool that adds a typed or drawn signature to any PDF.
• Phone: both iOS Files and Android's built-in PDF viewers support markup annotations, including a signature, directly on the screen.

None of these produce an audit trail. There is no record of when you signed, from what device, or that the file wasn't edited afterwards — fine for an internal form, risky for anything you might need to prove later.

If someone emailed you a PDF and asked for a signature back, check first whether they actually want a signed image or whether they sent it through a proper e-signature link (DocuSign, PandaDoc, or a Signavos signing link look like a secure webpage, not an attachment). If it is a real signing link, open it and sign there — it is faster and it produces the proof both sides will want later.

If it is a plain PDF attachment, using Preview or Fill & Sign to add your mark and emailing it back is the accepted norm for low-stakes paperwork. For a lease, a contractor agreement, or anything with money attached, ask whether they can re-send it through a proper signing link instead — it protects you too.

A typed or drawn signature pasted into a PDF proves nothing on its own — anyone with the file could have added it. The moment a document matters enough that someone might dispute who signed it or whether it was changed afterwards, you need three things a plain PDF editor does not give you: a secure link tied to one recipient, a timestamped record of every step, and a checksum proving the final file matches what was signed.

That is what a dedicated e-signature tool adds, and it is the difference explained in what is an electronic signature audit trail?

1. 01Upload the PDF (up to 40 MB). It is validated, scanned and hashed on upload.
2. 02Place the fields the signer must complete — signature, initials, date, name, text or a checkbox — and mark which ones are required.
3. 03Enter the recipient's name and email and send. One credit is debited at this point, not before.
4. 04They receive a secure link, sign in the browser with no account, and you get the completed PDF plus a Certificate of Completion the moment they finish.

No subscription, no per-seat fee — sending costs from $0.50 per signature depending on the credit pack you buy. The full walkthrough, including what happens if the recipient never opens the link, is in the product guide.

If you need someone else to sign the PDF, send a PDF for e-signature without a subscription: Signavos emails a secure signing link and charges per signature.