Chú thích PDF

Commenting on a PDF Without Changing What It Says

Most of the time you open a PDF to react to it, not to rewrite it: flagging a clause for a colleague, grading a student’s submission, marking the passages worth citing in a research paper, or telling a client where to look before they sign. None of that needs the underlying document to change. It needs a layer on top of it.

That’s what Annotate PDF is for. Highlight a line, underline a term, drop a sticky note next to a paragraph, stamp a page APPROVED, or draw an arrow at whatever you’re pointing at — all of it sits above the original content. The text the author wrote stays exactly as it was; your markup is the only thing that moves.

Every Way to Mark Up a Page

A markup toolkit built around reviewing, not rewriting.

The Free Annotation Tools, Compared

A markup pass is often the most sensitive layer of a document — the negotiation position, the grade, the unfiltered feedback. Here’s what you’re trading for convenience elsewhere.

Why a Highlight Sometimes Doesn’t Survive the Trip

A PDF viewer can choose to skip the markup layer entirely, and plenty do. Print dialogs routinely offer a "document only" mode that drops every highlight and comment on the way to paper. Paste a page into a layout program and the geometry you drew can vanish while the text underneath stays put. None of that is corruption — it’s just a layer nobody made mandatory.

Annotate PDF sidesteps the problem on export: your highlights, notes, and stamps are drawn directly into the page rather than left as an optional overlay. What you see before you download is what every viewer, every printer, and every recipient sees afterward. Keep the original file if you’ll want an unmarked copy later — baking the markup in is permanent by design.

Your Markup Never Leaves Your Browser

A document worth marking up is usually a document you’d rather not hand to a stranger’s server — a contract mid-negotiation, a manuscript under review, a patient record, a student’s graded work. Uploading it just to add a highlight means trusting that server with the file and everything you wrote on it.

OxygenPDF’s annotation tools run entirely in your browser. The PDF loads locally, your markup is rendered locally, and the file you download never passed through anywhere else. Close the tab and nothing about the document or your comments remains anywhere but on your own device.