I don’t have use for a tool like this anymore but at one point I did. Postman is the big fish in this game but it requires an account (a real head scratcher that one) on top being sluggish so I started looking for alternatives. I ended up on Insomnia. It was alright.
But it looks like this particular genre of software is predisposed to turning into SaaS garbage. Insomnia started requiring an account recently. A tool called Bruno posed itself as an alternative and now it has announced a pricing structure so it is not far fetched it will become garbage too.
I found this alternative. The codebase seems mature and the author says they are not going to paywall it. Strangely I never found this software when I was looking for it.
Postwoman is another option. No account needed, can be self-hosted.