Free PDF Annotation Tool

The PDF Annotation Tool is a free online tool that add text notes, highlight boxes, and stamps to pdf pages. specify position, color, and opacity. download the annotated pdf instantly.. It runs entirely in your browser with no installation or sign-up needed.

Text notes (with position and font size), highlight boxes (with custom color and opacity), and stamps (DRAFT, APPROVED, etc.).

Yes. Add as many annotations as needed before applying them all in a single pass.

Yes, completely free. All processing happens in your browser using pdf-lib.

Absolutely. The PDF Annotation Tool processes everything client-side in your browser. No data is uploaded to or stored on any server. Your content remains private on your device at all times.

Yes, the PDF Annotation Tool is fully responsive and works on smartphones and tablets. You can use it on any device with a modern web browser -- no app download required.

No account or registration is needed. Simply open the PDF Annotation Tool in your browser and start using it immediately. There are no sign-up walls or usage restrictions.

Since the PDF Annotation Tool processes files in your browser, the size limit depends on your device's memory. Most devices can handle PDFs up to 50-100MB without issues.

Simply enter your input in the provided field, adjust any settings to your preference, and the tool will process it instantly. You can then copy the result to your clipboard or download it.

The PDF Annotation Tool works in all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. For the best experience, use the latest version of your preferred browser.

This tool places markups by percentage of the page size rather than fixed pixels, so a note lands in the same relative spot whether the page is A4, US Letter, or a custom size. The origin is the top-left corner: X is measured from the left edge and Y from the top, so Y=0 is the very top of the page and Y=90 sits near the bottom. A text note takes a single X/Y point, while a highlight box takes an X/Y corner plus a width and height, all as percentages from 0 to 100. Stamps ignore coordinates entirely and are always centered automatically. If a note lands slightly off, nudge the X or Y value a few points and apply again. Upload your PDF above and enter the X and Y values to drop your first annotation exactly where you want it.

A highlight box draws a translucent colored rectangle over a specific area, the way you would swipe a highlighter across a paragraph. You choose its position, width, and height as percentages, pick any color (the default is yellow), and set the opacity from 0.05 to 1 — about 0.4 keeps the text underneath readable. A stamp is different: it overlays one large bold word across the center of the page at 48-point size and roughly 60% opacity, in red, blue, green, or orange, and whatever you type is shown in capitals like DRAFT, VOID, or APPROVED. Use a highlight to call attention to a region of content, and a stamp to label the whole page's status. Both are added to the same annotation list, so you can combine them. Add either type above and apply them together.

Opacity controls how see-through your highlight box is, on a scale from 0.05 (barely visible) to 1 (fully solid). At full opacity the colored rectangle covers the text completely and makes it unreadable, which defeats the purpose of a highlight. A value of around 0.4 — the default here — strikes a good balance: the color is clearly visible but the words beneath still show through, just like a real highlighter pen. If your PDF uses a dark or busy background, drop the opacity a little lower; for a faint pastel tint, raise it slightly. Because the markup is drawn on top of the page rather than replacing it, the underlying text is never deleted. Pick your color and opacity above, apply the highlight, and check the downloaded file to confirm the text stays legible.

Text notes accept any font size from 6 to 72 points, with 12 as a sensible default that reads like normal body text. The right size depends on the page and the purpose: 10 to 12 points suits an inline comment alongside existing content, while 18 to 24 points works for a heading-style note meant to stand out at a glance. Keep in mind that larger sizes take more horizontal room, so a long note in big type can run off the edge of the page; for wordy comments, lower the size or shorten the text. Notes are drawn in dark blue so they read as added remarks rather than original copy. Set the size in points above, place the note with X and Y percentages, and apply it to see exactly how it fits on the page.

No. This tool never overwrites the file you upload. When you hit Apply, it reads your original locally, draws every annotation in your list onto a copy using the pdf-lib library, and saves that copy with an _annotated suffix added to the filename — so your clean original stays exactly as it was on your device. You can stack as many markups as you like across different pages, such as a note on page 2, a highlight on page 5, and a stamp on the cover, then write them all in a single pass. If you don't like the result, just discard the annotated copy and start again from the untouched source. Because everything happens in your browser, nothing is uploaded and no server-side version is created. Add your annotations above and download the new _annotated file when you're done.