Sign PDF Online — Free Digital Signature Tool
Add your digital signature to PDF documents securely. Draw your signature, upload an image, or use text signatures — all processing happens locally in your browser.
Why Choose Our PDF Signature Tool?
Complete Privacy
Your PDF never leaves your device. Online signature tools upload documents to remote servers. LocalPDF signs documents locally using client-side processing.
Multiple Signature Types
Draw freehand signatures with mouse/trackpad, upload signature images (PNG/JPG), or use typed text signatures. Maximum flexibility for your signing needs.
No Account Required
Most signature tools require account creation and limit free signatures. LocalPDF works instantly without signup and has no usage limits during beta.
Legally Binding
Digital signatures added with LocalPDF are as legally valid as hand signatures in most jurisdictions (check local laws for specific requirements).
Professional Output
Signatures are embedded as high-quality vector/raster images positioned precisely where you want them. No pixelation or quality loss.
Batch Signing
Sign multiple PDFs with the same signature without re-drawing or re-uploading. Ideal for contracts, invoices, and batch document workflows.
Key Features
How It Works
100% Private Sandbox: Your files never leave your device. All processing happens locally in your browser's secure memory.
Frequently Asked Questions
Are my files uploaded to a server?
Never. All processing happens 100% locally in your browser. Your files stay on your device, ensuring total privacy and security.
Is there a limit on file size?
There are no artificial limits. The only constraint is your device's available memory. Most modern computers and phones can handle large PDF files without issues.
Does it work on mobile devices?
Yes! LocalPDF Sanctuary is fully responsive and works on iOS, Android, and tablets through any modern web browser.
Technical Architecture: How it Works
Zero-Knowledge Architecture
Our system is designed so that your data is never seen by anyone else. Processing happens in the browser's secure memory space.
WebAssembly Performance
We use high-performance WebAssembly modules to achieve desktop-grade PDF processing speeds directly in your web browser.