Postman is a rest client that started off as a Chrome browser plugin but recently came out with native versions for both Mac and Windows. At a high level, you can use it to send a post request to your web server and it gives you the response back. It allows you to set up all the headers and cookies your API expects, then check the response when it comes back. That's its basic functionality, but it also has a lots of other features built into it, like excellent cookie management that can sometimes be hard to manage with other API tools. Postman supports every HTTP method you can think of — including some you might even know about.