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YOLO TXT to COCO JSON Converter
Merge individual YOLO .txt label files or a ZIP archive into a single, standardized COCO JSON dataset file. Restores absolute pixel coordinates and builds a clean category mapping for PyTorch, Detectron2, and MMDetection.
Convert annotation format
Upload one annotation file and download it in a different format.
One file only
COCO JSON, YOLO TXT (ZIP), Pascal VOC XML, CVAT XML, LabelMe JSON, CSV, TSV, or JSONL.
Quick conversions
Converting YOLO Normalized Labels to COCO JSON
YOLO Format (Per Image .txt)
YOLO stores one txt file per image with normalized values:
0 0.500000 0.500000 0.250000 0.400000 1 0.200000 0.800000 0.100000 0.150000
COCO JSON Format (Unified)
COCO combines all images, categories, and bboxes into one JSON:
{
"images": [{"id": 1, "file_name": "img1.jpg", "width": 1920, "height": 1080}],
"categories": [{"id": 0, "name": "person"}],
"annotations": [{"id": 1, "image_id": 1, "category_id": 0, "bbox": [720, 324, 480, 432]}]
}Key Benefits of LabelOp In-Browser Converter
- Zero Server Uploads: Safe for proprietary, medical, and private datasets.
- Detectron2 & MMDetection Ready: Clean COCO standard structures.
- ZIP Batch Support: Drag and drop your entire labels directory at once.
- Instant Download: Converted in seconds directly in WebAssembly/JS.
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