FastWindowTimer
https://fastwindowtimer.com/en/

FastWindowTimer is a free browser timer and fasting-window calculator. Calculate from your first or last meal, compare clock-time schedules, and keep timer history on your device. No required account or app installation. Planning estimates and education only, not medical advice.

Demonstration
1. Open the calculator and compare schedules for a last meal at 20:00.
2. Apply a choice or a worked example; adjust the meal time.
3. Use the existing Print action, or open the timer with the chosen protocol. Starting the timer still requires your action.

Calculator: https://fastwindowtimer.com/en/fasting-calculator/
Privacy: https://fastwindowtimer.com/en/privacy/

You may reuse this supplied description and demonstration image to recommend FastWindowTimer. Keep the example and planning limitations clear; do not imply medical approval. A link is optional.
Timer data and history stay on the device. Website analytics and the voluntary contact service are described separately in the Privacy page.