So you want to get started with API testing?
First of all, good for you! It is pretty hard to avoid APIs if you work in software and testing them is an important part of creating high quality software. If you haven’t done stuff like this before it can be pretty scary, but I think you will find that it can also be rewarding. There is something exciting about learning how the pieces of an application come together and being able test and explore and API can help you understand this better.
But how do you get started?
Well, try using an API. There are many, many public APIs that you can look at. Here for example, is a big list of public APIs. Find something that is pretty simple and that you find interesting. Maybe the cat facts API. Download Postman or another easy to use API tool and put in a URL and press send.
Making your first API call is pretty easy and from there, just try stuff. Try different endpoints. See what happens when you change things. Google for answers when you get stuck. I think you will pretty quickly find that you can do a few different things and are starting to get an understanding of the way APIs work.
The next step might be to find out what APIs your team has that you can test. Do the same thing. Find an endpoint you can get started with and try stuff. Look at what it can do and change things to see what happens. Search for internal documentation. Talk to developers and architects. See what you can figure out about it and how it works.
At first it will be a frustrating experience. You will feel like you have no idea what is going on and you will get stuck frequently. Just leave it for a little while and then come back again, perhaps the next day. Keep trying things. Look at it from new angles. Grow your understand of the pieces of the product. Ask lots of questions. Over time you will find that things become more and more clear and then you’ll be doing it. You will be an API tester!