Hi, I have a project that currently only use in my company but as it scale, it need to integrate with other app and that need to use my API for calculation. But my current setup is that there's authorization whatsoever.
When I started I don't think much as it's a local system and no need to expose API to the public so I didn't have anything secure. Now, I want something simple like signature but without using the passport or JWT. I just want to keep it simple. How to achieve that?