Professional PDF Editor

Two libraries do the heavy lifting inside the page. PDF.js renders each page of your document to a canvas so you can see it, and a Fabric.js layer sits on top of that canvas holding everything you add: text boxes, freehand strokes, shapes, highlights, redaction covers and signatures. Because that layer is separate from the rendered page, objects stay movable, resizable and rotatable, and can be reordered forward or backward, copied, pasted and deleted until you are satisfied.

When you download, pdf-lib rebuilds the document, writing your annotation layer into the page content and applying the structural changes you made. Page reordering is handled by a drag-and-drop list, and merging pulls pages from the additional PDFs you select into the same output.

All of this happens in JavaScript on your own machine. The file you open never leaves the browser, which matters for contracts, medical letters and anything else you would not want to send to a third-party service simply to add a signature.

Suppose you receive a twelve-page contract as a PDF, need to sign page nine, mark the file as confidential, number the pages and return only the relevant section.

Open the file and use the page navigator to reach page nine. Select the signature tool, draw your signature in the pad, and place it over the signature line, dragging the corner handles to size it. Switch to the text tool to type the date beside it, choosing Helvetica at 12 point in black. If the contract carries an old reference number, the redact tool covers it with an opaque block.

Next, apply a watermark with the text CONFIDENTIAL, setting its angle to 45 degrees, colour to light grey and opacity low enough to leave the text readable beneath. Add page numbers with the prefix Page, positioned bottom centre, starting at 1.

Finally, use split to produce a new file from pages 8 to 12 only, then download. The output is a five-page PDF carrying your signature, watermark and numbering.

Understand what redaction does here. The tool draws an opaque cover over the area, which hides the content visually in the exported file, but treat it as visual masking rather than a forensic guarantee. For genuinely sensitive material, redact the content in the source document before it is ever converted to PDF.

Added text is drawn onto the page as new content rather than reflowing the original paragraphs, so this is not a word processor. Editing a typo in the document's existing body text means covering the old text and typing the replacement over it, which works but will not match the original font metrics perfectly. Choose the closest available font and check alignment at full zoom.

Large documents and high page counts take longer to render and rebuild, since the work happens on your own processor. Always open the downloaded file and review every edited page before sending it, particularly signature placement and watermark opacity, because a watermark set too dark can obscure the text underneath.