@mrob Your very first start point should be Postman, after that you go to the language you need...

I've been using Restclient via Rails. Everything has been working fine with user credentials for years but I'm trying to replace with oauth now.

POSTMAN makes it easy to configure the proper oauth call so you can compare it to whatever your doing with Restclient. Though I dislike having a separate (external) tool - I tend to test out TBA connections with jest code-based integration tests instead.

Sounds good- I'll work on postman for a bit! I was using http://lti.tools/oauth/ (which also is a bit sketchy to use, was going to re-set all keys/secrets once set up) to do the comparison before.