User Guide
A simple, private tool for stamping PNG signatures (or any image) onto PDFs. Everything runs locally in your browser — your files never leave your computer.
1. Open the editor
Click Open Editor in the top bar.
Note: The first time it loads, you need an internet connection — it pulls in two small libraries (pdf.jsandpdf-lib) from a CDN. Your browser caches them afterwards, so it works offline after that.
2. Load one or more PDFs
- Drag & drop one or several PDF files anywhere onto the window, or
- Click Open PDF(s) in the top bar and select one or more files.
Each loaded PDF appears in the Documents list in the left sidebar, showing its page count and how many images you've placed. Click a document to view and edit it.
- The currently selected document is highlighted.
- Click the × next to a document to remove it from the list (this does not touch the original file on disk).
- To add more PDFs later, drop them onto the “Drop more PDFs here” zone in the sidebar.
3. Save signatures to the sidebar (one-time setup)
The Signatures section of the sidebar is a personal library that is remembered across sessions (stored in your browser). Add a signature once and it's always there.
To add a signature:
- Drag a PNG onto the “Drop PNG signatures here” zone in the sidebar, or
- Click Add signature in the top bar.
For best results, your signature PNG should have a transparent background so only the ink shows over the PDF. See the Signature Guide for how to make one.
Each saved signature shows a thumbnail. Click its × to forget it.
4. Place a signature on a page
- Drag a signature from the sidebar directly onto the spot on the page where you want it, or
- Drag a PNG/JPEG file straight from your computer onto a page (this places it once without saving it to the library).
Once placed, an image can be:
| Action | How |
|---|---|
| Move | Click and drag it |
| Resize | Drag the round handle at its bottom-right corner (keeps aspect ratio) |
| Delete | Click the red × badge, or press Delete / Backspace while selected |
| Deselect | Click an empty area of the page |
You can place as many images as you like, on any page, in any document.
Sizes are remembered
When you resize a signature that came from the sidebar, that size becomes its new default. The next time you drop the same signature — on this document or any other — it comes in at the same size. This makes it easy to stamp a consistent signature across a whole batch of documents.
5. Save your work
Click Save All. Each loaded PDF is exported with the images baked in, named:
contract.pdf → contract_signed.pdf
invoice.pdf → invoice_signed.pdfThe files download to your browser's Downloads folder.
Multiple downloads: The first time you save several files at once, your browser may ask “Allow this site to download multiple files?” — click Allow.
Same name twice: If a_signed.pdfalready exists in Downloads, the browser appends(1),(2), etc. rather than overwriting.
Tips & troubleshooting
- Nothing happens when I drop a PDF. Make sure the file really is a
.pdf. Try the Open PDF(s) button instead. - My edits disappeared after reloading. Loaded PDFs and their placements are not saved automatically — reloading clears them. Your signature library is remembered, but the documents you're working on are not. Save before closing.
- The signature has a white box around it. Your PNG isn't transparent. Follow the Signature Guide to remove the background.
- Everything is local. No file is uploaded anywhere. You can even disconnect from the internet after the libraries have loaded once.