June 17, 2026
How to Sign a PDF Online for Free
Adding a signature to a PDF doesn't require Adobe Acrobat or a paid eSign service. Here's how to sign a PDF online in seconds.
Two Types of PDF Signatures
A visual signature is an image of your handwriting stamped onto the page. A cryptographic eSignature is a digitally verified certificate embedded in the file — the kind used by DocuSign, HelloSign, and similar services. For most everyday documents (forms, authorisation letters, internal approvals), a visual signature is sufficient. For legally binding contracts where authenticity must be verified, use a dedicated eSign service.
How to Create a Signature Image
Sign your name on white paper and photograph it. Or sign on your phone's notes app and screenshot it. Crop tightly around the signature, save as PNG. A transparent background gives the cleanest result when overlaid on the PDF. JPEG also works but the white background will show.
How to Add the Signature to a PDF
Upload your PDF and your signature image to Papyrio's Sign PDF tool. Choose whether to sign only the last page or every page. The signature is placed bottom-left at a standard margin. Download the signed PDF — the signature is embedded into the page content using PyMuPDF.
Making the Signature Permanent
After signing, the signature image is part of the page but could technically be covered or moved by a full PDF editor. To lock it permanently, run the signed PDF through Flatten PDF. Flattening bakes all page content into a single layer with no editable elements.
Sending the Signed Document
For email, check the file size after signing. If it's large, compress it first. For documents going to a legal department or a government office, check whether a visual signature is accepted or whether a cryptographic eSignature is required — requirements vary by jurisdiction and context.