Free Image Annotation Tool for COCO & YOLO Export

AI Training Data Generator for Computer Vision and Image Machine Learning

Free Image Annotation Tool for Machine Learning

The best free image annotation tool for creating machine learning datasets. This image annotation tool requires no signup and no installation — it runs entirely in your browser. Add image metadata, draw precise annotations, and export in COCO JSON, YOLO, or HuggingFace format. Perfect for image machine learning projects of any scale.

Use our free image metadata tool to organize and label your training data efficiently. Whether you are building an object detection model, training a diffusion model, or annotating medical images for research, this tool provides everything you need in one place — completely free.

Annotation Tools

  • Polygon Annotation - Draw precise boundaries around objects with unlimited vertices for complex shapes like cells, tumors, or irregular regions
  • Bounding Box (Rectangle) - Quick rectangle annotations for object detection datasets in COCO and YOLO formats
  • Circle Annotation - Mark circular regions like cells, colonies, or round structures with a single drag
  • Pin (Point) Annotation - Place labeled point markers for keypoint detection and landmark annotation
  • Arrow Annotation - Draw labeled arrows to highlight specific features or directional relationships
  • Auto-Annotation - AI-powered cell detection with Cellpose for automatic nuclei and cytoplasm segmentation

Export Formats

  • COCO JSON Export - Industry standard format for computer vision with full segmentation masks and bounding boxes
  • YOLO Format Export - Normalized coordinates ready for YOLOv5, YOLOv8, and other YOLO model training
  • HuggingFace JSONL Export - Metadata format for diffusion models, vision transformers, and HuggingFace datasets
  • Training CSV Export - Spreadsheet format with normalized coordinates, labels, and metadata for custom ML pipelines
  • Training Package - All-in-one ZIP bundle with image hash verification for reproducible datasets

All export formats include bounding boxes, segmentation data, labels, confidence levels, and image metadata. Import annotations back from any format to continue your work.

Use Cases

  • Object Detection - Create bounding box and polygon datasets for training YOLO, Faster R-CNN, SSD, and other detection models
  • Medical Image Annotation - Label tumors, tissues, cells, and pathological regions on histopathology slides, X-rays, and microscopy images
  • Histopathology & Pathology - Annotate breast cancer slides, tissue samples, and biopsy images with precise polygon boundaries
  • Cell Colony Tracking - Use time-lapse comparison to measure colony growth patterns and annotate changes over time
  • Scientific Research - Label biological specimens, geological samples, satellite imagery, and other research data
  • Diffusion Model Training - Generate image-caption pairs with metadata for Stable Diffusion, DALL-E, and other generative AI models
  • Instance Segmentation - Create pixel-level annotations for semantic and instance segmentation model training

How to Use This Free Image Annotation Tool

  1. Upload your image - Drag and drop or click to select any JPG, PNG, or TIFF image at any resolution
  2. Select an annotation tool - Choose from polygon (A), rectangle (R), circle (C), pin (P), or arrow (L) using keyboard shortcuts
  3. Draw and label - Click to annotate regions, add text labels, set confidence levels, and write notes
  4. Add metadata - Write captions, negative prompts, tags, and categories for your training data
  5. Export your dataset - Download in COCO JSON, YOLO, HuggingFace, CSV, or Training Package format

Why Choose This Free Annotation Tool?

Unlike LabelStudio, LabelMe, Roboflow, CVAT, or VGG Image Annotator, this free image annotation tool requires no signup, no installation, and no server setup. It runs entirely in your browser with full offline support. Your images stay private — nothing is uploaded to external servers unless you explicitly choose to save to your account.

Key advantages over other annotation tools:

  • Zero setup - No Docker containers, no Python environments, no server configuration. Open the URL and start annotating immediately.
  • Privacy first - Images are processed locally in your browser. No data leaves your machine unless you opt in.
  • Multiple export formats - One tool supports COCO, YOLO, HuggingFace, CSV, and Training Package formats. No format conversion scripts needed.
  • Import and continue - Re-upload any image and import its metadata file to restore all annotations exactly as they were.
  • Scale calibration - Measure real-world distances in pixels-per-millimeter for scientific and medical imaging applications.
  • Keyboard shortcuts - Professional-grade workflow with single-key shortcuts for every tool: A, P, C, R, D, H, L, F.