LimelightHelpers.java) for FRC robots using WPILib. It exposes every Limelight camera feature through static methods — no build system plugins, no additional dependencies, and no extra setup beyond dropping the file into your project.
Communication happens entirely over NetworkTables. As long as your robot and Limelight are on the same network, the library works without any configuration.
LimelightLib v1.14 requires LLOS 2026.0 or later on your Limelight camera. Check your firmware version in the Limelight web interface before use.
Supported pipeline types
LimelightLib supports all Limelight pipeline modes:- AprilTag / Fiducial — multi-tag and single-tag 3D pose estimation
- Retroreflective — track reflective tape targets with tx/ty angular offsets
- Color — color-threshold target tracking
- Neural classifier — identify game pieces or field elements by class
- Neural detector — locate and bound multiple objects simultaneously
- Barcode — decode QR codes, Data Matrix, and other barcode formats
MegaTag2 localization
LimelightLib supports MegaTag2, Limelight’s gyro-fused localization algorithm. By supplying your robot’s current heading each loop, the Limelight fuses IMU data with visual AprilTag observations to produce highly accurate, rotation-stablePose2d estimates you can feed directly into WPILib’s pose estimator.
Data classes
The library includes several public static classes for structured access to camera output:| Class | Description |
|---|---|
LimelightResults | Full parsed JSON output from a single camera frame |
PoseEstimate | A Pose2d with timestamp, latency, and per-tag fiducial data |
RawFiducial | Per-tag data from the pose estimate array (ID, distance, ambiguity) |
RawDetection | Neural detector result with class ID and bounding box corners |
RawTarget | Raw retroreflective contour from the rawtargets NetworkTables key |
IMUData | Limelight internal IMU values (yaw, pitch, roll, gyro, accelerometer) |
Get started
Installation
Add LimelightHelpers.java to your WPILib project
Quickstart
Read your first target and get a pose estimate running fast
AprilTag localization
Use fiducial tags to determine your robot’s field position
API reference
Full reference for every method and data class