PDF Annotator: Highlight, Comment and Draw on PDFs
Highlight, underline and strike out text, add comments, draw and add shapes on any PDF, then save real PDF annotations. Free online PDF annotator, no upload, no sign-up.
Most tools never upload your files
How to annotate a PDF online
Reviewing a contract, grading a paper, giving feedback on a design or studying for an exam? PDF Annotator lets you mark up any PDF the way you would with a pen and a highlighter, then save it as a normal PDF that anyone can open. Highlight, underline and strike out text, add sticky note comments, draw freehand, and add rectangles, ellipses, lines and arrows in any color. It is free, needs no account, and your document never leaves your browser.
How to annotate a PDF online
- Open the PDF. Drop the file onto the page or click Choose file. The pages appear in a scrollable viewer with thumbnails on the side.
- Pick a tool. Choose Highlight, Underline, Strike out, Pen, Comment or a shape, and set its color, thickness and opacity.
- Mark up the pages. Drag across text to highlight it, click to place a comment and type it, or draw. Use Select to move or delete marks, and undo when needed.
- Save. Choose editable annotations or a flattened drawing, press Save annotated PDF and download the file.
Text markup that follows the words
Highlight, underline and strike out work like selecting text: drag from the first word to the last, and the mark snaps to each line of text in between, stopping at the characters you chose. The highlighted words are stored with the annotation, so reviewers can see what was marked in the comments list of their viewer. On scanned pages that contain only images, the mark covers the box you drag instead.
At a glance
| Item | Details |
|---|---|
| Price | Free, no sign-up, no watermark |
| Text tools | Highlight, underline, strike out |
| Other tools | Comments, pen, rectangle, ellipse, line, arrow |
| Saved as | Editable PDF annotations or flattened drawing |
| Works with | Acrobat, Preview, Edge, Chrome, Firefox and more |
| Privacy | Processed in your browser, never uploaded |
Editable annotations or flattened drawing
Editable annotations are the standard PDF comment types: highlights, underlines, strike outs, sticky notes, ink and shapes, each with its own appearance so it looks the same in every viewer. Others can reply to them, change them or delete them, which suits reviews and teamwork. Flattened drawing paints the marks into the page itself, so nobody can remove them; choose it for a final copy. Comments are always kept as notes so their text stays readable.
Your file stays on your device
The PDF is shown with pdf.js and written with pdf-lib, both running in your browser. Nothing is uploaded and nothing is stored, so the annotator is safe for contracts, medical documents, exams and other private files. Password protected PDFs need their password removed first.
Tips
- Need to change the text itself or add images? Use Edit PDF.
- Want to sign the document after review? Open it in Sign PDF.
- Scanned document? Run PDF OCR first so highlights snap to the words.
- Comparing two versions of a document? Try PDF Comparison.
- Hiding sensitive text for good? Use Redact PDF, because a highlight or a black box drawn on top does not remove the text underneath.
Features
- Highlight, underline and strike out text that snaps to the words
- Sticky note comments you can open in Acrobat, Preview, Edge or Chrome
- Freehand pen, rectangles, ellipses, lines and arrows
- Any color, thickness and opacity, with undo and redo
- Saved as real, editable PDF annotations, or flattened into the page
- Free, no sign-up, and your PDF never leaves your browser
Frequently asked questions
Are the annotations real PDF comments?
Yes. By default highlights, underlines, strike outs, notes, ink and shapes are saved as standard PDF annotations with their own appearance, so Adobe Acrobat, Apple Preview, Edge, Chrome and other viewers show them and let others reply to, edit or delete them.
What does Flattened drawing do?
It paints highlights, drawings and shapes into the page content so they can no longer be moved or removed, which is useful before sharing a final version. Comments stay as notes so their text is not lost.
How do I highlight text precisely?
Choose Highlight, Underline or Strike out and drag across the words, like selecting text. The mark snaps to the lines of text under your drag. On scanned pages without text, the mark covers the box you drag.
Can I undo a mistake?
Yes. Use the undo and redo buttons or Ctrl+Z and Ctrl+Y. With the Select tool you can also click any mark to move it or press Delete to remove it.
Will annotations already in my PDF be kept?
Yes. Existing comments and form fields stay in the file, and your new marks are added next to them.
Is my PDF uploaded?
No. The PDF is displayed with pdf.js and saved with pdf-lib in your browser. It is never sent to a server.