Here are some very useful tools that can assist you while developing, debugging and testing web APIs.
Runscope is in some ways similar to Postman, but it’s made to work with your production endpoints. You can configure it to run every day or every few minutes and let you know if some endpoint is behaving differently than expected. Tests are configured in a web interface. Apart from its tests functionalities it has a couple of other useful tools. For example you can setup a middleware that will capture requests and responses for inspection. It goes like this: suppose you are making a call to a third party API, you can send the request to Runscope, it will record everything about the request, send it to the third party, record the response and send it back to your system. It also offers libs that will make the whole process almost transparent to your system.
ngrok provides a way for you to expose your local environment to the web. There are many applications for this, one of the most interesting is testing integrations with web hooks. Requests made to ngrok can be routed to your local machine allowing you to assure everything is working before pushing to production. Another cool use case is being able to exposing an API under development to a mobile app.
RequestBin is a very simple service that will record requests. It’s just like the Runscope tool but it will not forward the call. The advantage is that there’s no setup needed, you simply create a URL to listen to calls and can start using it. This is a quick way to investigate if a client is doing requests correctly.