I looked over the home page and even then I couldn't make sense of it. Calling something an "API client" or an "Essential Tools for API Development" is utterly useless; every piece of software is an "API client". Putting "keyboard shortcuts" as a marketing point on your home page isn't exactly helping things either.

It looks like it's another of those HTTP call generator tools, like Postman but online. I guess the target audience is people who consider "API" to mean "HTTP calls", which is why it took me so long to get it.

Looks like a decent alternative for Postman now that Postman is forcing their online sync stuff down everyone's throats.

It's an API endpoint testing app, like Postman and Insomnia