Is my PDF uploaded to sign it?

No. The signature is drawn and embedded into the PDF entirely in your browser using pdf-lib. Your document is never uploaded to a server.

Can I place the signature on a specific page?

Yes. Choose the page number and a corner position, then adjust the size before stamping. The signature is embedded as a transparent PNG.

How do I add my signature to a PDF?

You can draw your signature with a mouse or touchscreen, type it in a signature font, or upload an image of your handwritten signature, then drag it to the right spot on the page and resize it. The signature is placed directly onto the document.

Is an electronic signature legally valid?

In many countries simple electronic signatures are legally recognized for everyday agreements under laws like the US ESIGN Act and the EU eIDAS regulation, though some documents require stricter qualified or notarized signatures. Check the rules that apply to your specific document.

Can I sign a PDF on my phone?

Yes. Because it works in the browser, you can draw your signature with your finger on a phone or tablet touchscreen, position it, and download the signed file — all without installing an app or uploading the document.

Does signing flatten the PDF so it cannot be edited?

Once you place the signature and export, it is drawn onto the page so it cannot be casually moved or removed in a normal viewer. Keep an unsigned copy if you may need to reposition elements later, since flattening fixes the layout.

What's the difference between drawing, typing and uploading a signature?

Drawing with a mouse or finger mimics your real handwriting, typing renders your name in a signature-style font for speed, and uploading uses a photo or scan of your actual signature. All three place the signature onto the page; choose whichever looks most authentic.

Sign PDF — Add Your Signature to a PDF Online

How to use Sign PDF

Add your handwritten or typed signature to any PDF document entirely in your browser — no server upload, no account required. Draw with a mouse or stylus, type your name in a script font, or upload a PNG image of your existing ink signature. Place and resize it anywhere on the page, then download the signed PDF. This tool creates electronic signatures; understand the distinction between electronic and cryptographic digital signatures before choosing the right approach for your use case.

Upload the PDF you need to sign.
Choose your signature input method: draw with mouse/touchscreen, type your name, or upload a transparent PNG image.
Position and resize the signature preview by dragging it to the correct location on the page.
Select which page to apply the signature to.
Click "Apply Signature" and download the signed PDF.

Your data never leaves your device — 100% private processing.

Electronic signatures vs. cryptographic digital signatures

Electronic signatures and digital signatures are legally and technically distinct. An electronic signature is any electronic mark indicating intent to sign — a drawn image, typed name, or scanned ink signature placed on a document. This tool creates electronic signatures, which are legally valid under the US ESIGN Act and EU eIDAS for most standard commercial and consumer agreements. A digital signature is a cryptographic mechanism using Public Key Infrastructure (PKI): a private key generates a unique hash bound to the document content, and a certificate from a trusted CA allows anyone to verify the document has not been altered since signing. Digital signatures are required for high-assurance contexts such as regulated healthcare, government filings, and qualified electronic signatures under eIDAS.

Electronic vs. digital signature comparison
Attribute	Electronic signature	Digital (PKI) signature
Creation method	Draw, type, or image upload	Private key cryptography (PKI)
Tamper evidence	None (image overlay)	Yes — hash detects any document change
Signer verification	Visual only	Certificate chain to trusted CA
Legal strength	Valid for most consumer contracts	Required for regulated/qualified contexts
This tool	✓ Supported	✗ Use a dedicated e-sign platform

How PDF signature fields and annotations work

The PDF specification (ISO 32000) defines a dedicated AcroForm signature field (field type /Sig) with an associated signature dictionary that carries the cryptographic hash, certificate chain, and signing timestamp when a PKI digital signature is present. This tool uses a simpler approach: the drawn or typed signature image is added as a Form XObject — an embedded image stream placed at the specified coordinates via the page's content stream. This is functionally equivalent to stamping a scanned wet-ink signature onto the page and is legally sufficient under the US ESIGN Act and EU eIDAS for most standard agreements.

Best practices for signature image quality

For the most professional result, sign on white paper with a black pen, photograph or scan at 300 DPI, and remove the white background in an image editor to produce a transparent PNG. A transparent PNG signature blends seamlessly onto any page background color. Avoid JPEG for signature images — JPEG's lossy compression introduces visible artifacts around signature strokes on white backgrounds at high zoom levels. Keep signature image files under 200 KB to avoid bloating the output PDF size unnecessarily.

Glossary

Electronic signature: Any electronic mark (drawn image, typed name, or scanned ink signature) that represents a person's intent to agree; legally valid under the US ESIGN Act and EU eIDAS for most contracts.
Digital signature: A cryptographic signature created with a private key and verifiable with a paired public certificate; provides tamper evidence and signer identity verification through PKI.
PKI (Public Key Infrastructure): A framework of certificates, certificate authorities (CAs), and cryptographic key pairs used to authenticate identities and create verifiable digital signatures.
AcroForm: The PDF interactive form technology (ISO 32000) that supports text fields, check boxes, and cryptographic signature fields (/Sig type) with embedded certificate data.
Form XObject: A self-contained PDF graphics object (an image or set of drawing commands) that can be stamped at any position on a page — the mechanism used to embed signature images.

Related PDF Tools

Add Page Numbers to PDF

Add page numbers to a PDF online. Choose position, starting number, and format, then download the numbered PDF. Free, private, in your browser.

e-Signature Generator

Create an electronic signature online by drawing or typing. Download a transparent PNG signature for documents and emails. Free and private.

Add Watermark to PDF

Add a text watermark to PDF files online. Customize font size, opacity, color, and position. Free, private, runs in your browser.

Merge PDF Files

Combine multiple PDF files into one in seconds. Free, fast, and private — your files never leave your browser, so your documents stay secure.

Split PDF

Split a PDF into multiple files or extract specific pages online. Free, private, and fast — your files never leave your browser during processing.

Word to PDF

Convert Word documents (DOCX) to PDF online in your browser. Private, fast, and layout-preserving for headings, lists, and paragraph formatting.

Explore all PDF Tools.

Sign PDF

How to use Sign PDF

Electronic signatures vs. cryptographic digital signatures

How PDF signature fields and annotations work

Best practices for signature image quality

Glossary

Related reading

Frequently Asked Questions

Why use Sign PDF?

Common use cases

Get weekly tool tips & updates

Related PDF Tools