This application was designed for countdowns to something or timer for something in a streaming application like OBS.
I personally often use it for AFK timers, but you’re free to use it as you want to.
You can choose timer duration, texts (before and after zero) and styles.
Then just add timer URL to OBS (or something else) browser source.
You can store a configuration key privately somewhere to reuse your configuration without somebody’s else intervention.
It’s free and open-source.
Favicon is from Icons8.