Free PDF Annotator & Editor
Updated July 2026
Add text annotations, highlights, and comments to PDF files in the browser. Draw, underline, and mark up documents — free online PDF annotator, no upload.
The PDF Annotator is a free online tool that add text annotations, highlights, and comments to pdf files in the browser. draw, underline, and mark up documents — free online pdf annotator, no upload.
Add text annotations, highlights, and comments to PDF files in the browser. Draw, underline, and mark up documents — free online PDF annotator, no upload. Results are immediate — no waiting, no loading screens, no account required.
How to use the PDF Annotator
Open the tool, enter your input, and get your result instantly. The interface is designed to be self-explanatory — no tutorial or manual needed. Where options exist, they are clearly labelled with sensible defaults. Your result can be copied to the clipboard or downloaded with a single click.
Tips for the best results
- Works on desktop, tablet, and smartphone — no app download required.
- Bookmark this page for instant access whenever you need it.
Who uses the PDF Annotator?
- Students annotating academic papers and textbook PDF excerpts for study notes.
- Reviewers marking up draft documents with comments and corrections for authors.
- Professionals signing and annotating contracts and forms without printing.
Common uses and search terms
The PDF Annotator is frequently used for: pdf annotator, annotate pdf, add text to pdf, pdf signature, pdf editor online. Whether you need a quick result or are working through a longer project, the tool handles all common variations without any configuration.
Why use Allio Tools's PDF Annotator?
Everything runs locally in your browser. No data is sent to a server, logged, or stored anywhere. The tool is completely free with no usage limits, no premium tiers, and no account required. Available in 11 languages and optimised for all screen sizes, the PDF Annotator works on desktop, tablet, and mobile with no app download needed.
See also:PDF Split & Merge · Rotate PDF · PDF to Text
How the PDF Annotator works
Upload your PDF file to open it in the annotator viewer.
Select an annotation tool: Text, Highlight, Underline, Strikethrough, Freehand Draw, or Comment box.
Click or drag on the PDF to add your annotation.
Save the annotated PDF to download it with all annotations embedded.
Tips & tricks
- If the output looks wrong, verify that your input uses the correct syntax for the expected format.
- Minified or compressed inputs work fine — the PDF Annotator pre-processes input before running the algorithm.
- Bookmark this page for instant access during debugging sessions. No login required on return visits.
Frequently Asked Questions
Are annotations embedded in the PDF or just an overlay?
Annotations are embedded as standard PDF annotation objects, compatible with Adobe Acrobat Reader, Preview (Mac), and all major PDF viewers. Recipients see your annotations when opening the file.
Can I add comments that other people can reply to?
Yes. Comment annotations appear as note icons on the page. Click to open the comment text. Most PDF viewers show comments in a side panel and allow replies, though the reply thread is typically managed by the viewer application.
Can I annotate a password-protected PDF?
Only if you have the password. Enter the PDF password when prompted to unlock it for annotation. The annotated output will retain the same password protection.
Are my PDF files sent to a server?
The annotator uses PDF.js and pdf-lib to render and annotate PDFs entirely in the browser. For files under 20 MB, no data is sent to any server. Larger files may use temporary server-side rendering.
Can I delete annotations after adding them?
Yes. Click any annotation to select it, then press Delete or click the trash icon to remove it. Undo (Ctrl+Z) also reverses the last annotation action.
Is the PDF Annotator free to use?
Yes, the PDF Annotator on Allio Tools is completely free with no sign-up or registration required. It works directly in your browser.
How does the PDF Annotator work?
Add text annotations, highlights, and comments to PDF files in the browser. Draw, underline, and mark up documents — free online PDF annotator, no upload. No data is sent to a server — everything runs locally in your browser for maximum privacy and speed.
Do I need to install anything to use the PDF Annotator?
No installation needed. The PDF Annotator runs entirely in your web browser on any device — desktop, tablet, or mobile.
Is my data safe when using the PDF Annotator?
Completely safe. The PDF Annotator processes everything locally in your browser. No input data, results, or usage information is ever transmitted to or stored on any server.
Does the PDF Annotator work offline?
After the page loads for the first time, the PDF Annotator works without an internet connection for all client-side processing. Tools that fetch live external data (such as DNS or network lookups) require an active connection.
Can I use the PDF Annotator on my phone or tablet?
Yes. The PDF Annotator is fully responsive and works on all modern smartphones and tablets. No app download is required — open your mobile browser, navigate to the tool, and use it exactly as you would on a desktop.
How do I share the PDF Annotator results?
Copy the result text or take a screenshot to share via message, email, or social media. The tool URL can also be bookmarked and shared directly — the PDF Annotator works for anyone with a modern browser, no account required.
Does the PDF Annotator work on all browsers?
Yes. The PDF Annotator is built with standard browser APIs and works on all modern browsers including Chrome, Firefox, Safari, and Edge — on both desktop and mobile. No plugins, extensions, or third-party software are required.
How do I save or export my results from the PDF Annotator?
Select and copy the result text to paste into any document or app. For image tools, a Download button saves the file directly to your device. Your browser's built-in screenshot function also captures results quickly. No account or login is required.
Works with ChatGPT, Claude, Cursor, GitHub Copilot, VS Code, Poe and more — 106+ tools, zero data collection.