Panlabel

The universal annotation converter

If you've ever written a one-off Python script to wrangle COCO annotations into YOLO format (or vice versa), panlabel is here to save you the trouble. It's a fast, single-binary CLI that converts between common object detection annotation formats — with built-in validation, clear lossiness warnings, and no Python dependencies to manage.

Panlabel is also available as a Rust library if you want to integrate format conversion into your own tools.

Note: Panlabel is in active development (v0.2.x). The CLI and library APIs may change between versions, so pin to a specific version if you're using it in production.

Installation

Homebrew (macOS / Linux)

brew install strickvl/tap/panlabel

Shell script (macOS / Linux)

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/strickvl/panlabel/releases/latest/download/panlabel-installer.sh | sh

PowerShell (Windows)

powershell -ExecutionPolicy Bypass -c "irm https://github.com/strickvl/panlabel/releases/latest/download/panlabel-installer.ps1 | iex"

Cargo (from source)

cargo install panlabel

Pre-built binaries

Download from the latest GitHub Release. Builds are available for macOS (Intel + Apple Silicon), Linux (x86_64 + ARM64), and Windows.

As a Rust library

cargo add panlabel

Quick start

# Convert COCO annotations to YOLO (auto-detects the input format)
panlabel convert --from auto --to yolo -i annotations.json -o ./yolo_out --allow-lossy

# Convert a YOLO dataset to COCO JSON
panlabel convert -f yolo -t coco -i ./my_dataset -o coco_output.json

# Convert a Pascal VOC dataset to COCO JSON
panlabel convert -f voc -t coco -i ./voc_dataset -o coco_output.json

# Convert Label Studio JSON to COCO JSON
panlabel convert -f label-studio -t coco -i export.json -o coco_output.json

# Convert CVAT XML to COCO JSON
panlabel convert -f cvat -t coco -i annotations.xml -o coco_output.json

# Check a dataset for problems before training
panlabel validate --format coco annotations.json

# Get a quick overview of what's in a dataset
panlabel stats --format coco annotations.json

# Compare two datasets
panlabel diff --format-a auto --format-b auto old.json new.json

# Sample a smaller subset for quick experiments
panlabel sample -i annotations.json -o sample.ir.json --from auto --to ir-json -n 100 --seed 42

What can panlabel do?

Command	What it does
convert	Convert between annotation formats, with clear warnings about what (if anything) gets lost
validate	Check your dataset for common problems — duplicate IDs, missing references, invalid bounding boxes
stats	Show rich dataset statistics in text, JSON, or HTML
diff	Compare two datasets semantically (summary or detailed output)
sample	Create subset datasets (random or stratified), with optional category filtering
list-formats	Show which formats are supported and their read/write/lossiness capabilities

Supported formats

Format	Extension / Layout	Description	Lossiness
ir-json	.json	Panlabel's own intermediate representation	Lossless
coco	.json	COCO object detection format	Conditional
cvat	.xml / annotations.xml export	CVAT for images XML annotation export	Lossy
label-studio	.json	Label Studio task export JSON (rectanglelabels)	Lossy
tfod	.csv	TensorFlow Object Detection	Lossy
yolo	images/ + labels/ directory	Ultralytics YOLO .txt labels	Lossy
voc	Annotations/ + JPEGImages/ directory	Pascal VOC XML	Lossy

Run panlabel list-formats for the full details.

list-formats shows canonical names (for example label-studio), while commands also accept aliases (for example ls, label-studio-json).

More convert examples

# COCO to IR JSON (lossless — no data lost)
panlabel convert -f coco -t ir-json -i input.json -o output.json

# IR JSON to TFOD (lossy — requires explicit opt-in)
panlabel convert -f ir-json -t tfod -i input.json -o output.csv --allow-lossy

# Auto-detect input format from file extension/content or directory layout
panlabel convert --from auto -t coco -i input.csv -o output.json

Getting help

panlabel --help              # See all commands
panlabel convert --help      # Help for a specific command
panlabel -V                  # Show version

Documentation

Want to go deeper? The full docs are readable right here on GitHub:

• Documentation home — start here
• CLI reference — every flag and option
• Format reference — how each format works
• Tasks and use cases — what's supported today
• Conversion and lossiness — understanding what gets lost
• Contributing — we'd love your help
• Roadmap — what's coming next

Contributing

Contributions are welcome! Whether it's a bug report, a new format adapter, or a documentation fix — we appreciate the help. For major changes, please open an issue first so we can discuss the approach.

See the contributing guide for details on the codebase structure and how to make changes.

License

MIT — see LICENSE for details.