My friend came to me and asked if I knew of anyway to get a fake api up quickly with some data so that as he taught his students they had an API to actually hit and get data. I knew of a few public apis that served content like Pokemon info or comic characters, but didn't know of any that let you setup your own content. So he was going to have to setup a Node JS or PHP api and then getting it running on a server.
This gave me an idea, why not create a simple web app that let you create api endpoints and just hard code the response. I used Laravel for most of my projects during that time so I made a quick version of the app for him to use for his class. I then decided it was probably a tool other developers could use at different times. For example, if you were a frontend developer waiting on another developer to finish up the backend API you could quickly mock out the api so you could fully test your frontend code. So I decided to make it a little prettier and make it available to anyone with a Github account.
Over the last few years I have seen it this app used for everything from schools, like in my friends case, to even someone using it for a web accessible settings file for an open source web app. With thousands of users and thousands of endpoints created I'm sure there are uses I can't even think of. Hopefully it will help you in a time of need.