Neon Stop Clock

Neon Stop Clock is a browser-based count-up / multi-interval countdown timer with configurable visual and audible alarms.

It is designed for situations where time discipline matters — for example meetings, presentations, workshops, or timed exercises — allowing presenters or facilitators to stay on schedule without constant manual monitoring.

The timer supports up to six sequential intervals. In countdown mode, the clock triggers a visual and/or audible alarm at the end of each interval, making it suitable for structured sessions with predefined time blocks.

Features

• Count up or countdown modes
• Up to 6 configurable intervals
• Visual alarm (neon flash effect)
• Audible alarm (Web Audio API)
• Adjustable colour, size, and volume
• Fully client-side (no dependencies)

Demo

https://johnfullerroot.github.io/neon-stop-clock/

Usage

Select mode

• Enable Count Up to use the clock as a stopwatch.
• Enable Count Down to configure one or more timed intervals.

Configure intervals (Count Down mode)

• Set the duration for Interval 1 using the hours, minutes, and seconds inputs.
• Click “+” to add up to five additional intervals.
• Each enabled interval is added sequentially to the total countdown time.

Configure alarms

• Enable Visual Alarm for a flashing on-screen alert.
• Enable Audible Alarm for a repeating tone.
• At least one alarm must be enabled when countdown intervals are set.

Customise display

• Adjust Colour to change the neon hue.
• Adjust Size to scale the timer display.
• Adjust Volume when audible alarms are enabled.

Control the timer

• Click Start to begin timing.
• Click Stop to pause.
• Click Reset to clear all intervals and return to the initial state.

License

GPL-3.0-only