Printing a document, signing it, scanning it and emailing it back is an absurd amount of work for one signature. This places a photograph of your signature directly onto the PDF, removing the white paper background so it looks like ink on the page rather than a pasted photograph.
Your file never leaves your device. It is read and edited by JavaScript running in this tab. Nothing is uploaded or stored.
Enter your details
Result
Fill in the fields above and your result will appear here.
What the Sign PDF does
The signature image is processed before placement: pixels lighter than a threshold become transparent, the image is cropped tightly to the ink, and the result is embedded as a transparent PNG. That is what makes it sit on the document naturally instead of appearing in a white box.
Be clear about what this is. It is a visible signature image — the electronic equivalent of signing a printout and scanning it, which is accepted for everyday business use across India. It is not a cryptographic digital signature.
How to use this tool
- Sign on plain white paper with a black or dark blue pen, using a reasonably thick nib.
- Photograph it in even daylight, keeping the paper flat and the camera square to it.
- Add both files here — the PDF and the signature photo.
- Enter 0 for the page to sign the last page, or a specific page number.
- Set the width and position, press Sign PDF, and adjust if it landed wrongly.
How the background is removed
Every pixel's luminance is calculated:
L = 0.299 R + 0.587 G + 0.114 B
L above 205 → made fully transparent (the paper)
L at or below → kept (the ink)
The image is then cropped to the bounding box of the
remaining ink, with a small padding, and embedded as a
transparent PNG.
This is why the signature needs dark ink on white paper
in even light — shadows are read as ink.
Worked example
Example: signing a contract
| Page | 0 — the last page |
| Width | 25% of the page (about 52 mm on A4) |
| Position | 60% across, 12% up |
| Result | signature above the signature line, bottom right |
A signature at 25% page width is roughly the size most people sign at on paper. Larger than 35% tends to look wrong.
What your result means
This is a visible signature, not a digital certificate. Widely accepted for business correspondence, vendor forms and internal approvals.
For anything requiring a legally recognised digital signature — MCA filings, income tax returns, GST, e-tendering — you need a Digital Signature Certificate from a licensed Certifying Authority on a USB token. No browser tool can produce one.
If the background is not fully removed, the photograph was too dark or unevenly lit. Retake it in better light.
Important considerations
- Use a black or dark blue pen with a reasonably thick nib. Light or very fine strokes may be treated as background and disappear.
- Photograph in even daylight. A shadow across the paper will be read as ink and appear as a grey patch.
- Store your signature image carefully — it can be reused by anyone who obtains it.
- Adding a signature invalidates any existing digital signature on the document.
- For a signature already sized for a form, the signature resizer prepares it to exact pixel and KB requirements.
- Some organisations specifically require a DSC. Check before relying on an image signature for anything formal.
Limitations of this tool
- Password-protected PDFs cannot be opened without the password.
- Processing happens in your device's memory, so very large documents can be slow.
- Existing text cannot be edited or removed — these tools add content on top of the page.
- This is a visible image signature, not a cryptographic digital signature under the Information Technology Act.
- Background removal uses a fixed luminance threshold, so poorly lit photographs may not clean up well.
- One signature on one page per pass.
Frequently asked questions
Is a signature added here legally valid in India?
It is a visible signature image, equivalent to signing a printout and scanning it, and is widely accepted for ordinary business use. It is not a digital signature under the Information Technology Act — that requires a Digital Signature Certificate from a licensed Certifying Authority.
Why does my signature have a grey background?
The photograph was unevenly lit or too dark, so the paper was not light enough to be treated as background. Retake it in even daylight on plain white paper.
Is my signature uploaded anywhere?
No. Both the PDF and the signature image are processed entirely in your browser. Given how sensitive a signature is, this is exactly why the tool works this way.
How do I sign the last page without knowing its number?
Enter 0 for the page number — the signature goes on the last page, which is where it usually belongs.