ankurdotio/testdog ? reverse-engineered prompt

Build me a production ready Node.js and Express API server called Testdog, meant for people to plug into side projects, demos, and MVPs.

I want it to feel like a real open source backend that serves a collection of free APIs, with a clean modular structure, authentication where needed, and sensible rate limiting. Keep it easy to explore, easy to contribute to, and simple to run locally. Include good defaults, basic documentation, environment setup, and a clear way to add new APIs later without turning the codebase into a mess.

Please make the project clean, well organized, and ready for production use, with tests and developer tooling in place. If you need to check current best practices or library docs online, go ahead and do that. The main goal is a solid API server people can clone, run, and extend without much friction.