Bruno

According to them:

Bruno is a fast and Git-friendly opensource API client, aimed at revolutionizing the status quo represented by Postman, Insomnia, and similar tools out there.

I have used it countless times now to test my local AWS running api's. Or other APIs. I love you can also set 'prerequests', so for example if you would need oauth, and need to get a 'token' first, you can setup it that Bruno does this on every requests. Neat!

Postman vs Bruno: https://www.usebruno.com/compare/bruno-vs-postman

https://docs.usebruno.com/
https://docs.usebruno.com/auth/oauth2-2.0/client-credentials