How it works
Your strokes are captured by signature_pad on an HTML canvas. When you click sign, the canvas is exported as a transparent PNG and embedded into the chosen page via pdf-lib's embedPng + drawImage. No data leaves your browser.
FAQ
Is this a legally binding electronic signature? It produces a visible signature on the PDF, which is what most everyday contracts (NDAs, rental agreements, school forms) need. It does NOT cryptographically sign the document, so it would not satisfy regulations that require certificate-based signatures (e.g. eIDAS QES, US ESIGN with notarization). For those, use a notary or a regulated provider.
How do I know where my signature will land on the page? Coordinates are in PDF points from the bottom-left of the page (PDF's native origin). A US Letter page is 612 × 792 pt. For a signature near the bottom-right of page 1, try X=350, Y=72, Width=180. Open the result and adjust if needed.
Will my signature ever be uploaded? No. The signature canvas, your PDF, and the merged output all live in this browser tab. There is no server-side processing.