PDF Annotation Tool

This free online PDF annotation tool adds sticky notes, highlights and shape markup to a PDF as genuine PDF annotation objects — the same kind of markup Adobe Acrobat's own commenting tools produce — not text and shapes flattened permanently into the page. That distinction is the whole point: a real annotation stays a separate, distinct object inside the file that any standards-compliant PDF reader recognizes, can display in its comments or annotations panel, and that the recipient can move, edit or delete on their end, exactly like a native "Add comment" or "Highlight text" tool would produce.

Four tools cover how people actually mark up a document during review. Sticky notes drop a small, click-to-place comment bubble anywhere on the page — type a note, and it's saved as a real Text annotation with genuine popup content, so it shows up in a reader's comment list rather than being an image baked onto the page. Highlight drags a translucent marker over a passage exactly like highlighting text in Acrobat, saved as a true Highlight annotation with proper quad-point coordinates. Rectangle and Ellipse draw clean outline shapes — a Square or Circle annotation — for circling a figure, boxing in a clause, or drawing attention to a specific region without obscuring what's underneath.

A dedicated Comments panel lists every sticky note across the entire document in one place, with the page number and a preview of its text, so reviewing or editing a long document's feedback doesn't mean flipping through dozens of pages hunting for where each note landed — click any comment in the list and it jumps straight to that page. Every annotation can be dragged to reposition it or deleted with a single click before you export anything.

Everything — rendering pages, placing annotations and building the real annotation objects into the saved PDF — runs entirely in your browser using PDF.js and pdf-lib. The document is never uploaded to a server, which matters for review workflows involving contracts, manuscripts, internal reports or anything else being marked up before it goes back to someone else.