Sign any PDF online in your browser. Free.
Open the PDF, draw or type your signature, drop it anywhere on the page, and download. Legally equivalent to a handwritten signature under E-Sign Act / VN Decree 130/2018, and your file never leaves your device.
Everything you need to know about signing PDFs online.
Why sign PDFs online instead of printing?
The print-sign-scan loop is the slowest part of any contract: print three pages, find a pen, sign, find a scanner that still works, scan to email yourself, attach to a reply. PDFCatalyst collapses that to thirty seconds — open the PDF, draw your signature once with your mouse or trackpad, save it, and place it on every contract you sign for the rest of the year. The signature is rasterised as a transparent PNG so it overlays the page exactly where you drop it.
Three ways to add a signature
Draw with your mouse, finger, or stylus on the signature pad — quadratic-curve smoothing means even a trackpad signature looks intentional, not jagged. Type your name in one of four cursive fonts (Caveat, Dancing Script, Sacramento, Italianno) for a printed-letterhead look. Or upload a PNG of your existing handwritten signature with a transparent background — best for company-stamped documents where the signature has to match a specific scan.
Legal validity (E-Sign Act + VN Decree 130/2018)
Electronic signatures are legally binding under the US E-Sign Act and Vietnam's Nghị định 130/2018/NĐ-CP for almost every commercial contract — employment agreements, NDAs, service contracts, vendor onboarding. Wills, real-estate transfers, and notarised documents still need wet ink in most jurisdictions; everything else is fair game. PDFCatalyst stores the signature image encrypted on your device only, so the audit trail (you signed it, on this device, at this time) lives in your browser, not on our servers.
Where signatures land in the exported PDF
pdf-lib embeds the signature as a transparent PNG image annotation in the output document, anchored to the exact PDF coordinates where you placed it. The image is rotated and scaled per the on-screen position, so what you see in the editor preview is byte-identical to what the recipient sees when they open the file in Acrobat, Preview, or any other PDF viewer. No flattening means the signature stays editable if you want to move it before downloading.
Reuse a signature across multiple PDFs
Tick "Save this signature for next time" once, and the signature image is encrypted and stored in your browser's IndexedDB. Future sessions on the same device pick it up automatically — open any PDF, click Sign, your saved signature appears as the default. Clearing your browser data wipes the saved signature; we never sync it to a server, so it can't leak through a credential breach on our side.
Long-tail signing workflows (e-signature, no-signup)
Most "sign PDF online" / "e-signature PDF free" searches lead to upsell-walled SaaS products that charge after the third document. PDFCatalyst is genuinely free for unlimited signatures because the work happens in your browser — there's no server cost to gate. After signing, fill the rest of the form fields (most contracts have a printed-name + date alongside the signature). Need to combine a signed contract with the original unsigned version for a legal audit trail? Use the merge PDF tool to bundle them. Adding a wet-stamp scan or company chop on top of the signature? Drop it in via add image to PDF.
When wet ink still wins (and when it doesn't)
Three categories still legally require wet-ink signatures in most jurisdictions: wills and codicils, real-estate transfers (deeds, mortgages), and notarised documents (powers of attorney, affidavits). Outside those, electronic signatures are equivalent to handwritten ones for employment agreements, NDAs, vendor contracts, service agreements, B2B SaaS, freelancer onboarding, internal HR forms, university paperwork, and almost every commercial use case. The Vietnamese Decree 130/2018/NĐ-CP, the US E-Sign Act (2000), and the EU eIDAS Regulation all converge on the same answer: a typed or drawn electronic signature with demonstrable consent is legally binding for ordinary commerce.
Sign PDF in 4 steps.
- 01Open the PDF
Drop your PDF onto the editor at /app or click to browse from your device.
- 02Open the signature pad
Click the Sign tool in the toolbar. Draw with your mouse/finger, type in a cursive font, or upload a signature image.
- 03Place on the page
Click anywhere on the page to drop the signature. Drag to move, corner-handles to resize.
- 04Download
Click Download to save the signed PDF. The signature is embedded as a transparent PNG.
Questions about this tool.
Sign your PDF in your browser. Free.
No signup, no upload, no watermark. Legally equivalent to a wet signature for almost every commercial contract — your file never touches a server.