I was using Postman and then wanted to try Fiddler too to compare REST call response. So this is a brief review on just the REST call feature. I used Fiddler for just a basic usage and it ran the calls that I wished to test. Overall it does that task for you.
I haven't tried the other features/tools or advanced features available, but it appears there are many, so I assume advanced developers are using or demanding such advanced features.
It wasn't intuitive to install (for Mac) users. I understand it is on BETA, so it's somewhat expected. It's also expected in general that installing things via terminal is not always straight forward, but installing a desktop app on Mac App on mac, users typically expect a one step that it would be just through Installation wizards.
It required installing Mono Framework first via terminal.. but there are directions on the Telerik blog to follow. If I recall, I had a few errors trying to install Mono that I wasn't able to resolve, but eventually tried to install Fiddler anyways, and it ran.
The other thing was the set up to get going also wasn't intuitive. Postman and other applications just have you post the url, the data and run. Fiddler, however had several options to enter your server information. I believe the advantage of that, is direct connection. For my purpose, I just needed to simply enter http url, info and run, so to quickly test.
It is possible because I am not too familiar with all the backend configuration which Fiddler gives options to, that it is confusing for me to fill out and make use initially. I would have to further investigate if I were to continue to test REST calls, using Fiddler tools.
If you're using Fiddler to test REST calls, it does do the job. If you're an advanced user, perhaps it appears there are many options available to make use of the Application's advanced features. If you're a Mac user, just read up on the installation process and the extra steps required.
I needed to use Fiddler to test a few REST calls, to see if the 3rd party APIs were running, properly. I wanted to verify that it wasn't just an error in my code, or running a REST call through command line. Over all, Fiddler returned the same data so I was able to verify that it was likely not an error on my end. So I trust that I can rely on checking with applications like Fiddler, that was developed by a team of experts.