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Home / PDF Tools / PDF Annotator

PDF Annotator

Highlight text, draw shapes, add notes and comments to your PDF files. 100% private — your file never leaves your device.

Drop your PDF here

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PDF
document.pdf
— — pages
Tools
Color
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How to Annotate a PDF

1

Upload Your PDF

Click the upload area or drag & drop your PDF file. All processing happens locally in your browser.

2

Choose Annotation Tool

Select from highlight, underline, strikethrough, freehand draw, text notes, rectangles, or circles from the toolbar.

3

Annotate Your Document

Click and drag on the page to apply annotations. Use the color picker and thickness controls to customize your markup.

4

Download

Click the Download button to save your annotated PDF with all annotations embedded directly into the file.

Available Annotation Tools

Highlight text with translucent color
Underline important content
Strikethrough for deletions
Freehand drawing with adjustable thickness
Add text notes and comments anywhere
Rectangle and circle shapes
9 annotation colors to choose from
Eraser tool to remove any annotation
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About the PDF Annotator

The FreeNestTools PDF Annotator is a free, browser-based tool that lets you add highlights, underlines, strikethroughs, freehand drawings, text notes, rectangles, circles, and other markup to any PDF document. Using PDF.js for rendering and the HTML5 Canvas API for annotation overlays, it provides a complete set of markup tools directly in your browser.

Annotations are a powerful way to review, collaborate, and communicate on PDF documents. Highlighting key passages helps with studying and research. Adding text notes provides comments and feedback without altering the original content. Freehand drawings and shapes let you point out specific areas or illustrate concepts. All annotations are embedded into the PDF so they appear in any PDF reader.

The tool includes 9 annotation colors, adjustable stroke thickness for drawing tools, an eraser to remove individual annotations, and support for multiple annotation types per page. You can annotate every page of your document, and all markup is preserved when you download the annotated PDF.

All processing happens entirely in your browser using client-side JavaScript. Your PDF files are never uploaded to any server—they never leave your device. This ensures your documents remain completely private and secure. There are no file size limits, no watermarks, no registration, and no hidden charges. Annotate as many PDFs as you need, as often as you like.

This tool is perfect for students annotating lecture notes and research papers, legal professionals reviewing contracts and case documents, business professionals providing feedback on reports and proposals, teachers grading assignments and providing comments, and anyone who needs to mark up PDF documents for review or study.

Supported annotation types: Highlight (translucent color overlay), Underline (colored line beneath text), Strikethrough (line through text), Freehand Draw (mouse or touch drawing), Text Notes (positioned text comments), Rectangle shapes, Circle shapes, and Eraser (remove any annotation). Each annotation can be customized with a choice of 9 colors.

Important: Annotations are embedded directly into the PDF file using standard PDF annotation objects, making them compatible with most PDF readers including Adobe Acrobat, Chrome's PDF viewer, and Preview on macOS. The tool preserves all existing content and formatting from the original PDF. Annotations cannot be edited after they are placed—use the eraser to remove and re-add them.

Frequently Asked Questions

A PDF annotator is a tool that lets you add notes, highlights, drawings, shapes, and other markup to PDF documents. Our free online PDF annotator works entirely in your browser — no software installation or file uploads required. You can mark up contracts, forms, academic papers, and any other PDF document quickly and easily.

Our PDF annotator uses pdf.js to render your PDF pages in the browser and provides an interactive canvas overlay on which you can draw, highlight, underline, add text notes, and insert shapes. When you download, we use pdf-lib to embed your annotations directly into the PDF file. All processing happens client-side — your files never leave your device.

Yes, absolutely. FreeNestTools PDF Annotator is 100% free with no hidden costs, no registration, no watermarks, and no file limits. You can annotate as many PDFs as you need, as often as you like, all without paying a cent.

Absolutely. All processing is client-side in your browser using pdf.js and pdf-lib. Your PDF files never leave your device. We do not upload, store, or access your documents. This is fully compliant with GDPR and CCPA privacy requirements. Your sensitive documents remain completely confidential.

Our PDF annotator includes a comprehensive set of tools: Highlight (mark text with translucent yellow or any color), Underline, Strikethrough, Freehand Drawing (draw freely with adjustable thickness), Text tool (add text notes and comments anywhere), Rectangle tool, Circle tool, and an Eraser tool to remove unwanted annotations. You can also choose from 9 different colors and 5 thickness levels.

Yes! You can choose from 9 colors including yellow, green, blue, pink, red, orange, purple, black, and white. You can also adjust the line thickness from 1px to 8px for drawing and shape tools. Simply click the desired color swatch or thickness button in the toolbar before annotating.

Yes, you can easily navigate between pages using the Previous and Next buttons, or by entering a specific page number in the input field. Each page maintains its own set of annotations independently, so your work on one page won't affect others.

Since all processing happens in your browser, the maximum file size depends on your device's available memory. Most modern browsers can handle PDF files up to 100 MB without issues. For very large files with many pages, close other browser tabs to free up memory for optimal performance.

Yes, you have multiple options: use the Eraser tool to click on any annotation and remove it individually, click "Clear Page" to remove all annotations on the current page, or click "Clear All" to remove all annotations from every page at once and start fresh.

Yes! The tool is fully responsive and supports touch events for drawing and annotating on smartphones and tablets. The interface adapts to your screen size for a smooth experience. Upload PDFs directly from your mobile device's file manager or cloud storage.

No installation required. The tool runs entirely in your browser using JavaScript. No software, no plugins, no registration needed. Just open the page, upload your PDF, and start annotating immediately. It works on Windows, Mac, Linux, and Chromebooks.

Once you have finished annotating, simply click the "Download Annotated PDF" button. Your annotations will be embedded directly into the PDF file using pdf-lib, preserving the original content while adding your markup. The annotated PDF will be downloaded to your device instantly with the filename originalname_annotated.pdf.

Yes. When you download, all your annotations — highlights, underlines, drawings, text notes, and shapes — are embedded directly into the PDF file using pdf-lib's drawing and annotation capabilities. The resulting PDF can be opened in any PDF reader (Adobe Acrobat, Chrome, Edge, etc.) with all annotations visible.
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