How to Add a Signature to a PDF Online

Signing a PDF used to mean printing, signing by hand, scanning and emailing — a process that could take 20 minutes. Today you can do it in under 60 seconds, entirely in your browser, without printing a single page.

Two ways to add a signature to a PDF

1. Draw your signature

Use your mouse, trackpad or finger (on touch devices) to draw your signature directly on the canvas. This is the quickest option and works well for a natural-looking signature.

2. Upload a signature image

If you already have a scanned or photographed signature saved as a PNG, you can upload it directly. For the best result, use a PNG with a transparent background so the signature blends naturally with the document.

How to sign a PDF in 5 steps

1. Open the Add Signature tool on ColaPDF.
2. Upload the PDF you want to sign.
3. Draw your signature on the canvas or upload a PNG image.
4. Choose where to place it (bottom right is the most common) and adjust the size.
5. Click "Apply Signature" and download the signed PDF.

Is a browser-based signature legally binding?

This depends on your jurisdiction and the context. In many cases a signature image placed on a document is accepted — particularly for internal approvals, informal agreements and documents where both parties agree to electronic signing. For legally binding contracts in regulated industries (financial, legal, medical), consider a dedicated qualified e-signature service that provides audit trails and complies with eIDAS or equivalent regulations.

Tips for a clean signature

• Draw slowly and deliberately — the canvas captures your movement in real time.
• Use a touchscreen stylus for the most natural result.
• For uploaded signatures, photograph or scan your signature on plain white paper in good lighting, then remove the background using any image editor.
• Adjust the size slider so the signature fits proportionally within the signature line.

Is my signature private?

Yes. Your signature and the PDF document are processed entirely in your browser. Nothing is uploaded to any server. When you close the tab, all data is gone.