usebruno/bruno ? reverse-engineered prompt

Build me a desktop application for exploring and testing APIs. It should be a lightweight and open-source alternative to tools like Postman or Insomnia.

The most important feature is how it stores data. Instead of a cloud account, I want it to save all the API collections directly on the user's filesystem as simple, plain text files. This is key because it allows teams to collaborate on the API collections using Git or any other version control system.

The app must be completely offline-only. I don't want any cloud sync features or required online accounts; user data privacy is critical and it should all stay on their device. It should have a clean interface for editing requests, managing different environments, and writing tests. Please make sure it's a cross-platform application that can run on Mac, Windows, and Linux.