Are there any CLI-only tools that are monetized, no web UI at all?

Hey folks,

I’m curious if there exist any command-line tools (CLI) that allow users to sign up, log in/out, manage subscription / billing, etc, entirely via terminal, without relying on any web UI or browser flow.

I’ve seen many tools that support CLI logins or actions post-login, but still use the web for checkout, payment, plan comparisons, account settings, etc. I’m wondering:

- Does anyone know a tool (open source or commercial) that handles full subscription lifecycle strictly via CLI?

- What are the technical or practical challenges people encountered in trying to build one?

- If this doesn’t exist widely, why do you think that is?

Thanks in advance for pointers or experiences you can share!