Annotate PDF

Highlight text, underline it, drop sticky notes and draw arrows on any PDF while the original pages stay as they were.

How to Save annotated PDF

1
Add your PDF
Drop the file into the box or pick it from your device. Your browser renders the pages together with an invisible text layer you can select with the mouse.
2
Highlight text or add a note
Drag across a sentence to highlight, underline or strike it out. Click anywhere to drop a sticky note, or draw an arrow, box or ellipse.
3
Save the annotated PDF
Press save. Every mark is written as a real PDF annotation and the file downloads with an -annotated suffix.

Real annotations, not a picture of them

Each mark you make is stored as its own PDF annotation object (Highlight, Underline, StrikeOut, Text, Square, Circle or Line) attached to the page and listed in the document's annotation array. Acrobat, Preview and every other viewer that understands the format shows them, lets the next reader move or delete them one by one, and can list them in a comments panel. The page content stream itself is never read or rewritten, so the original text, images and layout come out of the save byte for byte identical. That is the difference between commenting on a document and changing it.

Highlighting works on the real text

Highlights, underlines and strike-throughs follow the glyph positions taken from the page's text layer, not a rectangle you draw by eye. Selecting a sentence that wraps across two lines produces two separate quadrilaterals, one per visual line, as a viewer expects, and a phrase running across a column break does not smear a box through the gap. Sticky notes carry up to 2000 characters of text plus your name, and shapes carry a colour and a border width. Highlight opacity is adjustable from 10 to 100 per cent.

Where your file is processed

The PDF is opened, rendered and written by your own browser. It is never uploaded, never queued on a server and never stored anywhere we can reach. There is no account and no email step. When you close the tab, the file and your comments are gone from memory with it.

Frequently asked questions

How is this different from editing a PDF?

An editor prints new content into the page, where it becomes part of the document. This tool adds a separate annotation layer instead: the page underneath is untouched, and every mark stays a distinct object anyone can move, reply to or remove later.

Do the notes open in Adobe Acrobat?

Yes. The marks are written as standard annotation dictionaries defined by the PDF specification, with the appearance streams viewers expect. Acrobat lists them in its comments panel, shows the author name and opens each note on click.

Can someone delete my comments in another program?

Yes, and that is by design. Annotations are meant to be reviewable: any viewer with editing rights can move or remove them. If you need marks that cannot be pulled off the page, print them in with the flatten option instead.

Why can't I highlight text on a scan?

A scanned page is a photograph, so there are no glyph positions to follow and nothing to select. Run the file through OCR first to add a text layer, or mark the area with a box, an arrow or a sticky note instead.

Can I reopen the file here and keep annotating?

Yes. Annotations already in the file are kept as they are, and anything you add joins them in the same list. Nothing is replaced, so passing a document around a team accumulates comments instead of overwriting them.

Will the comments show up when I print?

Yes. Every mark carries the print flag, so highlights, underlines, shapes and note icons appear on paper and in PDF exports. Turn on the flatten option if you want them fused into the page for a viewer that ignores annotations.

Does my file go to a server?

No. Rendering the pages, reading the text layer and writing the annotated PDF all happen inside the browser tab. Nothing is uploaded, so a contract under review stays as private as the device it is sitting on.