PDF Digital Signature
FreeApply a cryptographic digital signature to PDF documents
Drop a PDF or click to browse
About PDF Digital Signature
A handwritten signature image proves little about who actually signed a document or whether it changed afterward. A cryptographic digital signature is different: it binds your identity to the file and flags any tampering. This tool applies that kind of signature to your PDF.
Upload your document and the tool attaches a cryptographic digital signature that readers can verify in standard PDF software. It runs in your browser, is free, and adds no watermark or account requirement. The file is handled only to apply the signature you requested, keeping the contents private to you throughout.
Common uses
- Signing contracts so recipients can confirm authenticity
- Certifying a report has not been altered after approval
- Adding a verifiable signature to official correspondence
- Sealing finalized documents before distribution
How to use
- 1
Upload your file
Click the upload area or drag & drop your file. Supports APPLICATION/PDF. Up to 50 MB.
- 2
Click "Process — PDF Digital Signature"
Click the process button. Your file is converted instantly on our secure servers.
- 3
Download your result
Preview and download your converted file. No watermarks, no quality loss, no expiry.
Why ToolHub?
- 100% Free — no account needed
- Works in your browser — no software required
- Instant results
- Secure and private
- No data stored
- Simple to use
FAQ
How is this different from drawing my signature?
A drawn signature is just an image. A cryptographic digital signature mathematically ties the file to a signer and reveals if the document is modified afterward.
Can recipients verify the signature?
Yes, standard PDF readers can check the signature and show whether the document is intact and properly signed.
Does editing the file break the signature?
Yes, that is the point. Any change after signing invalidates the signature, which is how tampering is detected.
Can I use PDF Digital Signature on mobile?
Yes — ToolHub is fully responsive and works on iPhone, Android, tablets and all modern browsers. No app install needed.