The short answer: to sign a PDF online for free, open OpenSign™, upload the PDF, drag a signature field onto the page, draw or type your signature, and download the signed file. It works in any browser, requires no software, and produces a legally binding signature with an audit trail.
How to sign a PDF online free
- Go to app.opensignlabs.com and sign in (free).
- Click Sign Yourself and upload your PDF.
- Drag a signature field onto the page where you need to sign.
- Draw with your mouse or finger, type your name, or upload a signature image.
- Add date, initials or text fields if needed.
- Finish and download the signed PDF — plus its certificate of completion.
Send a PDF for someone else to sign
Need a counterparty to sign? Use Request Signatures instead, add their email, place fields for each signer, and OpenSign emails them a secure signing link. You'll be notified when it's complete.
Why sign PDFs with OpenSign
- Free — sign unlimited PDFs yourself at no cost.
- No install — fully browser-based.
- Legally binding — ESIGN, UETA and eIDAS compliant.
- Open source — audit the code or self-host for sensitive PDFs.
- Audit trail — every signature timestamped and verifiable.
Open-source PDF signing
Because OpenSign is open source, it's a popular choice for teams that need self-hosted PDF signing to keep documents inside their own network. Explore the project on GitHub.
Ready to try it? Create a free OpenSign account and start signing documents in minutes — no credit card required. Prefer to run it yourself? OpenSign is 100% open source on GitHub.