Interval Timer

WHAT IT DOES

Interval Timer is a browser extension that displays a floating interval timer designed for high-intensity interval training (HIIT) and similar workout routines. You can set work duration, rest duration, number of rounds, and optional warm-up and cool-down periods. The timer alternates between work and rest periods, displaying the current round number and phase (warm-up, work, rest, cool-down, or done) with distinct colors for each phase: red for work, green for rest, yellow for warm-up, and purple for cool-down. Sound alerts play at each phase transition and when the timer reaches zero, keeping you informed without needing to watch the screen. The timer state persists across page loads, so you can close the page and come back to continue where you left off. The tool is ideal for HIIT workouts, Tabata training, circuit training, and any interval-based exercise routine.

WHERE IT RUNS

Interval Timer runs on any webpage, overlaying a floating panel that does not interfere with page content. It operates entirely in your browser as a lightweight userscript, using JavaScript's setInterval for timing. It works on any page, whether static or dynamic, with no external dependencies. All timer settings and state are stored locally using GM_setValue—no data is ever sent to any server.

HOW TO USE

After installation, open the floating panel by clicking the extension icon. The timer displays "00:00" initially. Configure your workout by setting the work duration (seconds), rest duration (seconds), number of rounds, and optional warm-up and cool-down durations (0 to disable). Click "Apply Settings" to save your configuration. Click the Start button to begin the workout—the timer will run through the warm-up (if set), then cycle through work and rest periods for the specified number of rounds, then play the cool-down (if set). The display shows the remaining time, current phase, and round number. Click Pause to pause the timer at any point, and Reset to stop and return to the idle state. Sound alerts play at each phase transition and when the timer completes. The timer state saves automatically, so if you close the page and reopen it, the timer continues from where you left off.

REAL MECHANISM — WHY THIS WORKS

Most interval timers require a dedicated app or website, often requiring you to leave your current page. Interval Timer uses a DOM-overlay architecture that works within your current page, providing a floating timer without context switching. The timer engine uses a state-machine approach with phases: idle, warmup, work, rest, cooldown, and done. Each phase has a duration set by the user. When the timer starts, the engine enters the first phase (warmup or work), decrements the remaining time every second, and updates the display. When remaining reaches zero, the engine plays a sound alert, transitions to the next phase based on the state machine rules, and resets the remaining time to the new phase's duration. The state machine handles the full workout flow: warmup → (work → rest) × rounds → cooldown → done. The persistence mechanism saves the current phase, remaining time, current round, and running status to GM_setValue on every update and on page unload. When the page is reopened, the timer restores its state and continues from the exact point it was at. Sound effects are generated using the Web Audio API, with short beeps for phase transitions and a longer chime for completion. This approach ensures accurate, persistent, and fully private interval timing without requiring any external services or network access.

THE PANEL

The floating panel is fully draggable and remembers its position per site, snapping to the edges of the viewport when dragged near them. You can collapse the panel to a small icon to minimize screen distraction and expand it back with a single click. The panel is resizable from the bottom-right corner, giving you more space to view the timer and settings. Press the Escape key to close the panel instantly. The panel remains open across page navigation within the same domain, maintaining your current view state. All preferences—panel position, timer settings, and timer state—are saved globally for a seamless experience.

PLEASE NOTE

Interval Timer requires the free BotGentz extension to be installed and enabled, as it relies on the cross-extension messaging API provided by BotGentz for DOM access permissions. Timer accuracy depends on the browser's JavaScript engine and may be affected by system load or tab throttling. The persistence mechanism ensures that the timer continues from the correct phase and remaining time when the page is reopened. Sound notifications require audio context to be initialized, which may require user interaction on some browsers. All timer data is stored locally in your browser using GM_setValue. No workout data, timing information, or usage data are ever sent to any server. The extension does not read, store, or transmit any personal information. It only calculates and displays timing values locally at your request.