I was thinking about an easy way to simulate various APIs, and I was looking for a reusable solution that doesn't require much setup and if possible is platform/language independent. The primary application would be in development of apps that rely on some API that has not been made available yet and in testing how one's system would respond to delayed API responses.

Introducing Reflex

Reflex is an experimental tool that does exactly that: it sends back whatever POST request body it receives allowing the user to adjust the delay, content type, or alter the way the output is produced. You can find usage instructions on its GitHub page, and the tool itself is available at https://hosting.kawaiidesu.me/reflex/.