PDF security
What does Sign PDF do?
Sign PDF places a typed, drawn or uploaded visual signature on one PDF page in the browser. You choose color, page, position and size. The source page appearance is kept. This is a visual mark only: it does not verify identity and it does not create a certificate-based digital signature. Rewriting a signed PDF can invalidate existing cryptographic signatures.
How to use Sign PDF
- 1Choose one PDF
Open Sign PDF and select a single PDF. Unlock the file first if a password is required. One PDF is accepted per task.
- 2Create the signature mark
Type a name, draw with the pointer, or upload a PNG or JPEG signature image. Set color for typed or drawn marks. Clear the pad if you need to start again.
- 3Place it on a page
Choose the page number, a nine-position placement and a small, medium or large size. Preview the mark before you apply it. The tool stamps one visual signature per run.
- 4Download the signed PDF
Inspect the page at the real size you will print or share. This output is not an identity check and is not a certificate-based digital signature.
Supported files and limits
- Output format: PDF
- Input: PDF, PNG or JPEG signature image
- Output options: typed, drawn or uploaded signature; color; page; position; size
- one PDF per task; does not verify identity or create a certificate-based digital signature
- Files stay on this device and are removed when you close the page.
The tool adds a visual signature mark only. It does not verify the signer and does not create a certificate-based digital signature. One PDF is accepted per task.
What the output keeps
- source page appearance
- visual placement of the signature
Source page appearance is retained. The signature image is drawn at the chosen page, position and size so the mark is visible in ordinary PDF readers.
What may change or be lost
- certificate validity when an existing signed PDF is rewritten
If the source already contained a cryptographic signature, rewriting the file can make that signature invalid. This tool does not add a validation certificate or a tamper-evident byte-range signature.
When not to use this tool
Do not use Sign PDF when a workflow requires a verified digital signature, a qualified certificate, or proof of identity. It is also the wrong tool for password protection, redaction or a tiled text watermark across every page.
If processing fails
If no signature is present, type, draw or upload one before continuing. Uploaded files must be PNG or JPEG. A page number outside the document is rejected. Encrypted PDFs must be unlocked first. Existing certificate signatures may not survive the rewrite even when the new mark appears.
Privacy boundary
The PDF and the signature image or strokes stay in this browser for the active task. They are not sent to a PDF Smart Kit application server. Close the page to clear the signature pad and the document from memory.
Testing evidence
Last tested: · Test browser: Desktop Chrome via Playwright Chromium · Product version: 1.0.0
Sample: Single-page PDF plus a PNG signature image · 1 pages
What was checked
- The download is a valid PDF.
- The chosen text, drawing or image appears on the selected page.
- The rest of the page remains readable.
Known failures and limits
- This is a visible appearance, not a certificate-based digital signature.
- The tool does not verify the identity of the signer.