Is it possible to create only backend RedwoodJS project? and not a full stack
You could, and I don’t know your actual use-case – but I’d advise against fighting the framework.
Build up your database and the backend as you desire – and then use the generators to create CRUD scaffolding for all your tables. It’s so easy (and nice) to have Admin pages for your database tables, and you don’t have to write any code. – Just don’t expose the web side
Backend only:
These pages should help you authenticate to, and use your backend here
You can expose webhooks also.
Cheers and welcome to RedwoodJS
Al;