HybVIO is a visual-inertial odometry system developed by Aalto University that fuses camera and inertial sensor data for real-time pose estimation, with an optional SLAM module. It implements classic computer vision techniques including feature tracking, optimization-based state estimation, and bundle adjustment. The codebase is research-oriented, published alongside a WACV paper for reproducibility, and intended as a baseline for VIO and VISLAM benchmarks rather than production use.