My side project osapy.com can be used for testing APIs, webhooks,etc. It doesn't make money yet, but as an indie hacker I would assume it can take a couple of years to get the product right and make any money. Great job on getting 7k EUR!
Actually - just tried your website and it doesn't work for me. I tried curl -H "Content-Type: application/json" -d '{"message":"hello world"}' https://8ef216dd46.endpoints.dev and nothing happened. Maybe check your logs.
Very cool. You can also use osapy.com to inspect 3rd party API requests. Or even combine Osapy with endpoints.dev. I wrote a blogpost how to do that for retool.
In which direction do you want to develop the website?
I've been frustrated with building API integrations and struggling to track down API call issues via Postman, e.g. what does a raw request really look like or where are my headers ending up. Interested to see if anyone finds this useful.