Please, allow using flat file http messages.
IntelliJ has a great build in http client that's using HTTP message files and otherwise has a similar feature set. But having to launch intellij every time is a real PITA.
I was going to post almost this exact comment. When I've got an Intellij IDE already open, it's the best tool for this job - and that's saying a lot as we've been developing HTTP clients for decades. But I often find myself banging out a curl command with too many -H clauses if nothing Jetbrains is already running.
For those who haven't used the Jetbrains HTTP client recently: maybe two or three years ago it was completely replaced and has been improved continuously since. Give it a try.