Insomnia ReST Client notes Russell Bateman February 2019 last update:

Simply put, Insomnia, which is free for the community version, is the most professional, polished and insanely straightforward ReST client available. Insomnia is a thick client (or full application binary), not a browser plug-in.

Insomnia web site, "Debug APIs like a human, not a robot. Finally, a ReST client you'll love!

Here's a link to support and documentation. For installation, see below.

Installation

For Macintosh and Windows, it's a download. For Linux, it's principally supported via Debian package, but it's also available via Snap and, likely, your distribution's Software Manager (or equivalent). It might help to run it from the command line. I have sometimes hung it trying to run from the panel (after putting it there).

How to add via the Debian package manager and install Insomnia—my experience. I got 6.5.3, which works well, by doing this:

1. Get root.

2. Add to sources:

   # echo "deb https://dl.bintray.com/getinsomnia/Insomnia /" | tee -a /etc/apt/sources.list.d/insomnia.list
   

3. Add public key used to verify code signature:

   # wget --quiet -O - https://insomnia.rest/keys/debian-public.key.asc | apt-key add -
   

4. Refresh repository sources and install Insomnia:

   # apt-get update
   # apt-get install insomnia
   # apt-get autoremove
   # apt-get autoclean