I have created a number of little tools that might be useful for you:
Mastodon API Tester
Use this to connect to a Mastodon API compatible server, like Mastodon itself, or a WordPress with the Enable Mastodon Apps plugin. It shows and (locally) records all HTTP requests so that you can see what’s going on.
URL: https://akirk.github.io/mastodon-api-tester/
Code: https://github.com/akirk/mastodon-api-tester
WordPress Playground Step Library
This is a tool for the WordPress Playground, this amazing piece of software that lets you run WordPress without a server, just in your browser. Because it can be hard to do more complex things with Blueprints, this tool provides you with a UI to quickly create blueprints and steps that do more than the ones that are provided by playground.
URL: https://akirk.github.io/playground-step-library/
Code: https://github.com/akirk/playground-step-library