If you're not technical: use the free online tool
If you're not a technical person and you're looking for a free way to add your signature to a PDF, use my online PDF signing tool. Draw your signature or choose an existing image, place it on the page and download the result. No installation or account is needed.
This adds a visual signature. Check that the recipient accepts that format; the tool does not create a certificate-based digital signature.
If you're technical, I'll explain how the drawing and PDF placement work after the steps.
How to add a signature to a PDF
- Open Sign PDF and choose your document.
- Choose an ink color and draw in the signature box, or select Choose image to use an existing signature image.
- Select the page where the signature belongs.
- Click or drag on the preview to position it.
- Adjust Scale, Rotation and Opacity as needed.
- Select Apply, download the PDF and reopen it to check the placement.
Keep the signature inside the intended space. It should not cover a date field, nearby text or the edge of the page.
If you're technical: how it works
If you're technical, this workflow has two main parts: capture a signature as an image, then embed that image on a PDF page.
A transparent canvas is useful for capturing pointer strokes without adding an opaque rectangle. The drawing can be exported as PNG and embedded in the document. My PDF implementation uses pdf-lib for image placement.
The coordinate conversion needs care. A browser preview commonly uses a top-left origin, while PDF drawing coordinates commonly use a bottom-left origin. Preview scale, page rotation and the signature's dimensions also affect the final position.
The implementation therefore maps the preview placement into page coordinates, applies scale and rotation, and saves a new document. A robust UI should check the saved result rather than relying only on a draggable preview overlay.
This pipeline changes page content. It does not create a cryptographic signature, an identity check or an audit trail.
A cleaner signature starts with a larger drawing
Drawing a tiny signature with a mouse often produces cramped strokes.
Try using more of the signature pad, then reduce its scale on the page. A phone, tablet or stylus may feel more natural than a touchpad.
Choose the ink color before drawing. Existing strokes keep the color they were drawn with, so changing the picker afterward does not recolor the whole drawing.
The drawn signature has a transparent background, which helps it sit on the page without an opaque white rectangle.
Visual signature versus digital signature
These terms get mixed together, but the capabilities differ.
| This tool adds | This tool does not add |
|---|---|
| A visible image of your handwriting | Certificate-based identity verification |
| A signature positioned on a PDF page | Cryptographic proof of who signed |
| A downloadable copy of the document | A signing audit trail or a lock against later edits |
Check the recipient's requirements. If they request a specific signing service or certificate workflow, a pasted signature image does not provide those features.
Fill the form before placing the signature
If the PDF contains interactive fields, complete those in Fill PDF forms first. Open the completed copy in Sign PDF afterward.
This makes it easier to inspect the final page as a whole: filled details, date and signature together.
If the file already contains a digital signature, pay attention to the tool's warning. Editing the PDF can affect validation of that existing signature.
Your signature stays in the local workflow
The PDF and signature are processed in your browser rather than uploaded to a conversion server. That was a useful constraint for a tool handling something as personal as a handwriting sample.
The final check is still yours: open the downloaded file, confirm the correct page is signed, and make sure the recipient accepts this signature format.
Do you find it easier to sign with a mouse, a finger or an existing image?
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