Bursta

Bursta is a free interval timer that runs in your web browser for boxing, muay thai, MMA, wrestling, HIIT, Tabata, and various breathing exercises. It keeps time by reading the wall clock every frame rather than maintaining a counter, ensuring accuracy even when browser tabs are throttled or stalled. The timer displays the current phase through color changes across the entire screen so you can read it from across a room. All numbers are editable, customizable with six color palettes, and settings are saved locally in your browser or shareable via URL. The site carries no advertising and has no paid tier or premium features.