# Sign a document

Canonical HTML: [https://pdfpix.com/guides/signing/](https://pdfpix.com/guides/signing/)

pdfpix can add a visible signature without uploading the file. It cannot create a certificate signature or prove who signed, because that needs a certificate from an authority the recipient trusts. An electronic signature is a picture of your name on the page. A digital signature is a cryptographic seal that breaks if the file changes. These guides explain which kind you need.

## Two things called a signature

An electronic signature is a picture of your name placed on the page. It proves nothing on its own. It is what most people mean when they say sign PDF, and for an internal form it is usually enough.

A digital signature is a cryptographic seal made with a certificate tied to your identity. It binds to the file contents, so any later change breaks it, and a reader can tell you who signed and whether the bytes moved since. To digitally sign a document you need a certificate from an authority the recipient trusts, which is why it is not a browser feature.

## What to use

For a certificate signature, use Adobe Acrobat Reader, which is free and handles certificate signing, or the signing flow your employer or government already provides. Many countries issue a national eID that signs directly.

For a drawn signature on a form, most operating systems can do it without extra software. Preview on macOS, the built-in reader on iOS and Android, and Acrobat Reader on Windows all place a signature image on a page.

## What pdfpix can help with

[Sign PDF](https://pdfpix.com/sign-pdf/) draws, types or uploads a visual signature, places it on the chosen pages and verifies that every mark is visible after the output is reopened. The file and signature stay in the tab. Use a certificate tool when the recipient needs identity or tamper proof.

## Questions and answers

### Can I sign a PDF on pdfpix?

Yes, if a visible signature is enough. Sign PDF adds a visual mark in this tab. It does not create a certificate signature, timestamp or audit trail.

### Is a drawn signature legally valid?

It depends on the jurisdiction and on what the parties agreed. In many places a plain electronic signature is binding for ordinary contracts, while land, wills and some official filings need more. Check the rule that applies to your document.

### What does a certificate signature prove?

That a specific certificate holder signed those exact bytes. If a single byte changes afterwards, the reader reports the signature as broken. A drawn image proves neither of those things.

### Can I merge a signed page back into the document?

Yes, but a certificate signature covers the file it was applied to. Merging produces a new file, and the signature will show as invalid. Merge first, then sign.

## Related pages

- [Add signature to PDF](https://pdfpix.com/sign-pdf/): Draw, type or upload a visual signature and place it on PDF pages without uploading the file. The file stays in your browser. No upload, no account needed.
- [How to sign a PDF](https://pdfpix.com/guides/how-to-sign-a-pdf/): Put a signature on a PDF and know whether it counts. Free, in your browser, with Add signature to PDF.
- [Add a signature to a PDF](https://pdfpix.com/guides/add-a-signature-to-a-pdf/): Add a drawn or typed signature to a page. Free, in your browser, with Add signature to PDF.
- [Digital vs electronic signature](https://pdfpix.com/guides/digital-vs-electronic-signature/): Know which kind of signature the person asking will accept. Free, in your browser, with Add signature to PDF.
- [Create a digital signature](https://pdfpix.com/guides/create-a-digital-signature/): Get a signature that a checker can verify. Free, in your browser, with Add signature to PDF.
- [Sign a PDF on your iPhone or Android phone](https://pdfpix.com/guides/sign-a-pdf-on-your-phone/): Sign a PDF on an iPhone, iPad or Android phone. Free, in your browser, with Add signature to PDF.
- [Sign a PDF on a Mac](https://pdfpix.com/guides/sign-a-pdf-on-a-mac/): Sign a PDF on a Mac with Preview or in the browser. Free, in your browser, with Add signature to PDF.
- [Sign a Word document](https://pdfpix.com/guides/sign-a-word-document/): Sign a Word file, or turn it into a PDF and sign that. Free, in your browser, with Word to PDF.