This may be slightly off topic, but what are some other small, lesser known websites like this one that people use regularly? For me, it'd be https://rubular.co

This may be slightly off topic, but what are some other small, lesser known websites like this one that people use regularly? For me, it'd be https://rubular.com https://rubular.com and https://crontab.guru https://crontab.guru. I've used those 2 sites pretty regularly across my entire career.