Tenderly helps you troubleshoot your Smart Contracts through real-time monitoring, analytics and alerting. They offer a "free forever" plan which is suited for experimentation and smaller hobby projects.
Protip: Their visual debugger and state inspector make it super simple to figure out why and where a transaction was reverted. Simply go to their Blockchain Explorer, paste your failed transaction into the search box and hit enter. Next up you'll get detailed data as to what happened during the execution and at which point the transaction was reverted (and why).