Highlight, draw, add text and notes to any PDF in your browser. No signup, no watermark, and your file is not uploaded.
or click to browse (Max 50MB)
This annotation tool processes your PDF in the browser. Other tools may work differently depending on the conversion.
Quick answer: To annotate a PDF online for free, open your PDF in the annotator above, pick a tool (Highlight, Text, Note, Draw, Rectangle, Circle, Line, Arrow or Image), click or drag on the page, then press Save Annotated PDF and download the file. It runs in your browser, so there is no signup, no watermark and no upload.
Want to annotate on a phone, iPad, Mac or Chromebook with built-in apps instead? Read the full guide: how to annotate a PDF on any device.
PDF annotation means adding highlights, comments, drawings, shapes or other markup on top of a PDF without rewriting the original text. People annotate PDFs to review contracts, give feedback on drafts, mark up lecture notes and research papers, proofread, and point out corrections on forms.
There are two common ways PDF annotations are stored. Desktop apps such as Adobe Acrobat Reader or Apple Preview usually save annotations as separate comment objects that you can later select, edit or delete. This free PDF annotator works differently: when you save, it draws your highlights, text, notes and shapes directly onto the page. That makes the marks look the same in every PDF viewer, but they cannot be edited as separate comments afterwards, so keep your original file if you may need to change them.
Highlight, text, notes, freehand drawing, rectangles, circles, lines, arrows and images (PNG or JPG), all in one toolbar.
Pick any color with the color picker and set a size from 1 to 20. The size controls line thickness, and for text it sets the font size.
Undo and redo with buttons or Ctrl+Z and Ctrl+Y, remove the last mark, or clear every annotation on the current page.
The PDF is rendered with PDF.js and saved with pdf-lib on your own device. Your document is not sent to a server.
Annotations are drawn into the page when you save, so they look the same in Adobe Reader, Preview, Chrome, Edge and phone viewers.
Use a mouse, trackpad, finger or stylus. Touch drawing works in mobile browsers such as Safari on iPad and Chrome on Android.
Each tool in this PDF annotator does one job. Here is exactly what each one adds to your page, so you can pick the right markup for review, study or feedback.
| Tool | How to use it | Best for |
|---|---|---|
| Highlight | Drag a box over any area. It adds a see-through color block (about 35% opacity). | Key sentences, figures, totals, form fields |
| Text | Click where the text should start, then type it in the prompt. | Corrections, labels, short answers |
| Note | Click to place a yellow comment box with a colored border and wrapped text. | Review comments, questions, reminders |
| Draw | Drag to sketch freehand lines. | Ticks, crosses, underlines, circling, handwriting |
| Rectangle and Circle | Drag to draw an outlined box or oval. | Framing a paragraph, chart or clause |
| Line and Arrow | Drag from the start point to the end point. | Underlining, pointing at a detail |
| Image | Choose a PNG or JPG; it is placed in the center of the page. | A signature image, stamp or logo |
Good to know: Highlight marks an area you drag over rather than snapping to selected words, which also means it works on scanned PDFs that have no selectable text. Text and notes are saved with a standard PDF font, so plain English and Western European characters work best. To place a handwritten signature you can also use our dedicated Sign PDF tool.
You can annotate a PDF on iPad or iPhone in two ways, and neither needs a paid app.
On iPhone and iPad, open the PDF in the Files app (or in the Books app) and tap the Markup (pen tip) button. Markup gives you pens, a highlighter, text, shapes and a signature tool, and it saves changes to that copy of the file. It is the quickest choice for files already stored on the device; this browser tool is useful when you want the same toolbar on every device, or a flattened PDF that looks identical in any viewer.
This annotator works in any modern browser, so the steps above are the same on every computer. Each platform also has a built-in option:
The right PDF annotator depends on what you need to do. Use this comparison to choose.
| Option | Cost | Install or account | Editable comments later | Where the file is processed |
|---|---|---|---|---|
| PDF Buddy annotator (this page) | Free | None | No, marks are flattened into the page | In your browser |
| Adobe Acrobat Reader | Free reader with commenting tools; advanced editing is paid | App install | Yes | On your device, with optional cloud storage |
| Apple Preview / Markup | Free, built in | None on Apple devices | Yes in Preview | On your device |
| Microsoft Edge PDF viewer | Free, built in | None on Windows | Partly | On your device |
| Upload-based online editors | Usually free with limits | Often optional sign-in | Varies | On the provider's servers |
Choose this free PDF annotator when you want quick markup with no install and no upload. Choose desktop software when you need editable comment threads, text-selection highlights or review workflows with several people.
Add notes, arrows, and comments to proposals, reports, contracts, and forms before sharing feedback with a team or client.
Highlight PDF notes, mark research papers, add study comments, and circle important ideas while reading course material.
Use text boxes, notes, highlights, and shapes to call out clauses, corrections, approvals, and follow-up questions.
Draw on PDF pages, point to mistakes, add correction notes, and mark personal PDF reminders before final export.
This PDF annotator opens, renders and saves your file inside your browser tab using PDF.js and pdf-lib. The document is not uploaded to our servers, so you can annotate PDFs without sending them anywhere. When you close or refresh the tab, the working copy is cleared.
50MB per file
PDF 1.3 through PDF 2.0, PDF/A
Highlight, Text, Note, Freehand Drawing, Rectangle, Circle, Line, Arrow, Images
This annotation tool processes your PDF in the browser
Chrome, Firefox, Safari, Edge, and all modern browsers
Close or refresh the tab to clear the active browser session
Use this PDF editor to annotate source files before or after AI-assisted review. Helpful next reads include How AI Is Changing PDF Editing and Document Management, PDF AI vs Traditional PDF Tools, and AI PDF Filler.
