Sign PDF Online – Add a Signature to PDF Documents
1. Choose a PDF
2. Create a signature
Typed text is converted into a transparent image in your browser so it looks the same in the exported PDF.
PNG, JPEG, or WebP · 10 MB maximum · 12,000 pixels maximum per side.
3. Review and download
No signatures added yet.
Choose a PDF or use the example. Then create a signature and add it to the current page.
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How to sign a PDF online
How the browser adds the signature
PDF.js renders the local page preview. PDF-lib copies the source document and draws each signature as a transparent PNG image at the position and size you selected. Positions are stored relative to the visible page, including rotated pages. The original file is not changed.
Drawn and typed signatures are converted into transparent PNG data locally. Uploaded images are decoded locally and normalized to PNG; optional near-white removal changes very light pixels to transparency. The page sets a 200 MB PDF guardrail and a 10 MB signature-image limit to reduce browser crashes. Available memory, PDF complexity, and mobile hardware can impose lower practical limits.
Important: A visible signature image is not the same as a certificate-backed digital signature. Laws and recipient policies differ, and some transactions require identity verification, consent records, audit trails, trusted timestamps, or an approved signing provider. This page does not determine whether a signature is valid for a particular purpose and does not provide legal advice.
Last implementation and sample-export review: 28 July 2026. Always open the downloaded copy and inspect every placement in the PDF viewer your recipient will use.
Frequently asked questions
Does my PDF get uploaded?
No. The selected PDF and signature are read and processed in browser memory, and the result is downloaded locally. Normal page resources such as analytics and ads may still make network requests, but the tool does not include your selected file or signature in those requests.
Is this a cryptographic digital signature?
No. This tool places a visible electronic signature image on the PDF. It does not create a certificate-based digital signature, verify identity, add a trusted timestamp, or provide tamper detection.
Is an electronic signature legally binding?
Electronic-signature requirements vary by country, transaction, consent, identity evidence, and document type. This tool only places the visible mark and does not establish legal validity. Check the rules and recipient requirements that apply to your document.
Can I sign more than one page?
Yes. Add a signature to the current page, move to another page, and add another. Each placement can be moved, resized, or removed independently before download.
Can I use a saved signature image?
Yes. Upload a PNG, JPEG, or WebP image up to 10 MB. The optional white-background removal is useful for a signature scanned on white paper; inspect the preview because pale ink can also be affected.
Will the tool change existing PDF content?
The export copies the PDF and draws signature images over the selected pages. Existing text and images are not intentionally rasterized, but modifying a PDF can invalidate an existing certificate-based digital signature, and unsupported forms, encryption, or unusual PDF features may not survive every editing workflow.
Are password-protected PDFs supported?
No password is requested by this page. If the browser libraries cannot open or modify an encrypted or permission-restricted PDF, use an authorized unlocked copy.
Is there a file-size or page limit?
The tool accepts PDFs up to 200 MB as a browser-safety guardrail. Available memory is the practical limit, so large image-heavy files may work better on a desktop with other tabs closed.
How do I place a signature precisely?
Drag the signature to move it and drag its lower-right handle to resize it. With the signature selected, arrow keys move it in small steps; Shift plus an arrow key moves it farther. The position and size are saved relative to the page.
What should I check before sending the PDF?
Open the downloaded file in the recipient's expected PDF viewer, inspect every signed page, confirm the signature is not clipped or covering important content, and verify whether the recipient requires a certificate-based signing service instead of a visible signature image.