Free tools
Practical tools for annotation and dataset workflows.
Start with practical tooling: clean format handoff, catch risky dataset patterns early, and remove friction before the next training run.
Annotation Format Converter
Convert one annotation file between COCO, YOLO, Pascal VOC, CVAT, LabelMe, and more.
Convert between COCO JSON, YOLO TXT, Pascal VOC XML, CVAT XML, LabelMe JSON, CSV, TSV, and JSONL.
- No login required
- Auto-detects source format
- Quick conversion shortcuts for popular format pairs
- ZIP output for per-image formats like YOLO and VOC
Annotation Merger
Merge many annotation files and turn them into one download target.
Merge Pascal VOC XML, LabelMe JSON, YOLO TXT, COCO JSON, CVAT XML, CSV, TSV, or JSONL.
- No login required for merge and download
- ZIP or multi-file input
- Per-image output when the target format needs it
- Bounding-box-first conversion for mixed export pipelines
Dataset Splitter
Split a COCO JSON file into train, validation, and test sets.
Upload one COCO JSON, set the split ratio, and download three ready-to-train files.
- Runs entirely in your browser
- Configurable train/val/test ratios
- Stratified sampling to preserve class distribution
- Download each split individually or all at once
Dataset Health Report
Check one annotation file for class imbalance, parse skips, and geometry risks.
Analyze COCO JSON, CVAT XML, JSONL, CSV, or TSV in one in-page report.
- Single-file health report in-page
- Class distribution and annotation density charts
- Warnings for duplicates, empty images, and out-of-bounds boxes
- Built for pre-training QA, not export conversion