Sign PDF
Sign a PDF: draw, type or upload your signature and add it anywhere on the pages.
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How to use Sign PDF
Key features of Sign PDF
Draw with a mouse, stylus or finger in a thin, medium or thick line; type your name in one of four handwriting fonts; or upload a PNG, JPG or WebP of a signature on paper. Drawn and typed signatures come in black, navy, blue or red ink; an uploaded image keeps its own colours.
For an uploaded photo or scan, Remove white background turns near-white pixels transparent, so the paper does not cover the lines under the signature. The signature is then cropped to its ink, as drawn and typed ones always are; with the box unticked, an opaque photo is placed whole.
The page is shown as a preview. Drag the signature onto the line, drag its corner to set a width from 30 to 400 pt, nudge it with the arrow keys, or use one of nine quick positions set 36 pt in from the edges.
Click + Add signature for a second signer or a witness, up to four in one pass, each with its own ink, size and pages. Sign one page, every page or a list such as 1-3, 5, and print today's date under any signature in one of four formats.
The page preview comes from pdf.js and the signing from pdf-lib, both running in your browser. Opening the Type tab loads the handwriting fonts from Google Fonts; that request names the fonts, never your name.
About Sign PDF
Sign PDF places a signature image on the pages you choose. Drawn, typed or uploaded, the signature becomes a PNG cropped to its ink, and pdf-lib embeds it once in the file; an opaque upload with Remove white background off is placed whole, paper included. The preview is the real page rendered by pdf.js, and the box you drag is the signature at the size it will print.
pdf-lib then saves the file again. Text, images and form fields are kept and the output opens in any PDF reader, but an existing certificate-based digital signature will no longer verify; the tool warns you when the file has one. What you add is a visible signature, like signing a printout, not a certificate, and it does not lock the document against later changes.
When to use Sign PDF
A lease, offer letter or consent form arrives by email to be signed and sent back. Open it here, draw or type your signature, drag it onto the signature line on the last page, tick the date if the form asks for one, and reply with the signed_ file.
An agreement asks for initials on every sheet. Draw your initials, shrink them with the width slider, move them to the corner where initials go and set Apply to to Every page. The mark lands at the same relative spot on each page, whatever its size.
You sign better with a pen, or already have a scanned signature. Photograph it on white paper in even light and use Upload image with Remove white background on; only the ink reaches the page.
A contract needs your signature and a witness's. Make yours, click + Add signature and make the witness's on the new tab. The boxes are numbered on the preview, so each goes on its own line and both are saved in one file.
A form with real fields is better filled with Fill PDF Forms, which lists every field by name. For text, shapes and a signature in one session, use the PDF Editor.
Tips and troubleshooting
- The preview opens on the last page, and a signature stays on the page it was placed on ("Page 2 only" under Apply to). The "Move signature to page 1" button above the preview brings the selected one to the page in view.
- With Every page or Custom pages, the signature keeps its position as a share of the page, so it sits in the same corner on pages of another size. A signature wider than a page is narrowed on that page only.
- Pages stored with a rotation, common in scans, are handled: the signature is drawn upright in the spot you chose, as the page is displayed.
- Over a form field, the signature becomes an annotation listed after the field, since an opaque field would cover it in the page content. The viewer built into Chrome and Edge still draws fields on top, so the preview outlines the signature in orange while it sits on a field; move it off the field if the file will be opened there.
- Only near-white pixels are removed from an uploaded image, so a photo in shadow can leave a grey patch. Retake it in daylight or crop it close to the signature.
- "Draw your signature in the box first." and the matching Type and Upload image messages mean the open tab is empty. Only the open tab's signature is used. With several signatures the message names the empty one, as in "Signature 2 is empty".
- Custom pages takes numbers and ranges separated by commas, such as 1-3, 5, 8- (8 to the end). A page outside the document, as in "Page 9 is outside 1-4.", or an empty box is reported and nothing is written.
- "This PDF needs a password to open" or, for a file that opens freely but limits editing, "This PDF is encrypted" appears when you choose the file. Remove the protection with Unlock PDF, then sign the unlocked copy.
How Sign PDF works in your browser
The PDF is read into memory with the File API, and pdf.js renders the page in view onto a canvas under the signature box. The box keeps its position as a share of the page's width and height and its size in PDF points, so resizing the window or turning pages does not move it. A drawn signature comes from pointer events on a canvas, a typed one is written onto a canvas in the chosen font and an uploaded image is drawn onto one with its near-white pixels cleared if you asked; each is cropped to its ink (an opaque upload with Remove white background off is used whole) and exported as a PNG.
pdf-lib opens the original bytes when you choose the file, and Sign & Download PDF embeds the PNG once. For each page, the box is converted to PDF coordinates through that page's own pdf.js viewport, which accounts for the crop box and any stored rotation, and the image is drawn there, turned where needed so it reads upright. The date, if chosen, is drawn in Helvetica under it. Over a form field, the same drawing goes into a Stamp annotation added after the page's fields. Nothing is uploaded: the file and the signature never leave the page. Apart from the page, its libraries from cdnjs and Google Analytics (only while it is switched on), the one other request is for the handwriting fonts when you open the Type tab.
Frequently asked questions
Is this a legally binding digital signature?
It is a visible signature image, the same as signing a printout. It is not a certificate-based digital signature and does not make the document tamper-evident; whether that is acceptable depends on the document and where you are.
Can I place the signature exactly on the signature line?
Yes. Drag it on the page preview to the line and drag its corner to resize it. The arrow keys move it one point at a time, or ten with Shift.
Can I type my signature instead of drawing it?
Yes. The Type tab shows your name in four handwriting fonts. The name is turned into an image in your browser, so the PDF does not need the font and every reader shows the same shapes.
Can I use a photo of my real signature?
Yes. Sign white paper, take a photo or scan and choose it under Upload image. Keep Remove white background on and only the ink is placed on the page. PNG, JPG and WebP files work.
Does it work on a phone or tablet?
Yes. The drawing box, the signature on the preview and its resize handle all respond to touch, so you can sign with a finger or a stylus and drag the signature into place.
Will the file get much bigger?
Only by the size of one PNG. The signature is embedded once and referenced from each page it appears on, even on every page, and a large uploaded photo is first scaled to at most 1600 pixels on its long side.
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