How to sign a PDF without uploading it anywhere

Think about which PDFs actually need a signature. A tenancy agreement. An offer letter. A loan form. A contract with a rate in it. A medical consent. Passport-number-bearing anything.

Now think about what "free online PDF signer" means mechanically: you upload that document to a server owned by someone you've never heard of, funded by something you haven't checked, in a jurisdiction you don't know, with a retention policy you didn't read.

The good news is that you almost never have to. Every major platform can sign a PDF locally, and has been able to for years.

macOS: Preview, which you already have

This is the best-kept-secret answer on the Mac.

1. Open the PDF in Preview.
2. Show the markup toolbar (the pen-tip icon), then click the signature icon.
3. Create Signature offers three routes: sign on the trackpad with your finger, hold a signature written on paper up to the camera, or sign on a connected iPhone or iPad.
4. Drag the resulting signature onto the page and resize it.

The iPhone route gives by far the best-looking result, you're writing with a finger or Pencil on glass rather than dragging on a trackpad. Signatures are saved to your keychain and reappear in Preview, Mail and anywhere else with markup.

You can also do this without opening Preview at all: select the file in Finder, press Space for Quick Look, and hit the markup button.

iPhone and iPad: Files, or straight from Mail

Open the PDF in Files or tap the attachment in Mail, then tap the markup icon and use the + button → Signature. Same signature store as the Mac if you're on the same Apple account.

For a scanned document, the Notes app's built-in scanner produces a much cleaner PDF than a photo, Notes → new note → camera → Scan Documents. It deskews and thresholds properly.

Windows, two local options

Microsoft Edge opens PDFs and has a Draw tool. It's crude but it is genuinely local, and it's already installed.

Adobe Acrobat Reader (the free one) has Fill & Sign, which is purpose-built for this and produces a much better result. Ignore the prompts to upload to Adobe's cloud, the local flow works without an account.

Linux: Xournal++ or Okular

Xournal++ is the one to use: import the PDF, draw or place a signature image, export back to PDF. Okular also does freehand annotation and can save annotations into the file.

The browser route, done properly

There is a legitimate version of an online tool: one where the PDF never leaves your machine because the processing happens in the page itself, in JavaScript, with no upload.

The distinction is not marketing language, it's observable. Open your browser's developer tools, go to the Network tab, and sign a document. If you see a request carrying your file, it was uploaded. If the tab stays quiet, it wasn't. Any tool making the claim should survive that test in ten seconds.

That's the bar we built our own PDF editor to meet: it runs entirely in the browser, so you can draw a signature, type one, or drop in an image of one, and also rewrite text, white out what shouldn't be there, fill in form fields and reorder pages, with nothing sent anywhere. No account, and it works offline once the page has loaded.

The part that actually matters legally

Almost everything above produces a drawn or typed signature image placed on a page. For the overwhelming majority of everyday agreements (rentals, freelance contracts, school forms, consent) that's what's being asked for and it's fine.

It is not the same thing as a digital signature, which is a cryptographic operation binding a certificate to the document so that any later modification is detectable. That's what standards like PAdES describe, and what enterprise e-signature platforms provide alongside an audit trail of who signed what, when, and from where.

The practical rule:

• Personal, commercial, everyday → a drawn signature is what's expected. Sign it locally and send it back.
• Someone specifically requires a certified or qualified electronic signature, or you need a defensible audit trail → you need a certificate-based signature, which means either a certificate you hold or a platform that provides one. Local Preview markup will not satisfy that requirement, and nobody should pretend otherwise.

If you're unsure which one you're being asked for, the request usually says so. "Please sign and return" means the first. "Please complete via our e-signature portal" means the second.

Two small habits worth having

Flatten before sending. An annotation layer can sometimes be moved or removed by the recipient's viewer. Exporting or printing to PDF afterwards bakes it in. In Preview: File → Export as PDF.

Don't email a signature image around as a file. A clean PNG of your signature on a transparent background is a small, reusable asset for anyone who receives it. Keep it in your signature store, place it in documents, and don't attach it on its own.

More free tools that run in your browser and upload nothing: ziyarex.com/tools.