Image Annotation Add text labels, arrows, and rectangular highlights to annotate images.

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Image Annotation

Add text labels, arrows, and rectangular highlights to annotate images.

Upload Image

Drop or select an image to annotate.

Add Annotations

Click to place text labels, draw rectangles, or add numbered markers.

Export

Download the annotated image with all markups baked in.

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What Is Image Annotation?

An image annotation tool for adding text labels, numbered markers, and rectangular highlights to any image. Perfect for marking up screenshots, creating instructional diagrams, highlighting areas of interest in photos, and adding callouts to documentation images. Each annotation is customizable with color, size, and position controls. The Canvas API composites all annotations onto the final image for a clean, professional result. All processing runs in your browser; no files are uploaded. Click to place each annotation, then export when ready.

Why Use Image Annotation?

Text labels, rectangles, and numbered markers
Customizable annotation colors and sizes
Click-to-place intuitive interface
Professional clean output for documentation

Common Use Cases

Bug Reports

Mark up screenshots to highlight UI issues and describe problems clearly.

Tutorials

Create step-by-step visual guides with numbered annotations.

Design Feedback

Add comments and highlights to design mockups for team review.

Documentation

Annotate screenshots for user manuals and help articles.

Technical Guide

Annotations are stored as an array of objects with type, position, text, and style properties. A transparent overlay canvas captures click events for placing annotations. On export, annotations are rendered onto a composite canvas: base image first, then rectangles with strokeRect, then text labels with fillText and background rects, then numbered circles.

Tips & Best Practices

1
Use contrasting colors against the image background
2
Keep label text concise for readability
3
Use numbered markers for sequential steps
4
Red rectangles draw attention to problem areas

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Frequently Asked Questions

Q Can I move annotations after placing?

You can remove the last annotation and re-place it. Each annotation is added sequentially.

Q How many annotations can I add?

There is no limit — add as many labels, markers, and rectangles as needed.

Q Can I change annotation color?

Yes, select your preferred color before placing each annotation.

Q What output format?

Annotated images are exported as PNG with all markups composited.

Q Can I annotate screenshots?

Absolutely — screenshots are the most common use case for this tool.

About This Tool

Image Annotation is a free online tool by FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration or installation required.