I want to API key secure. How to secure data

Design help Data API
1

Hello,
currently i am working on one project.
and i have create mobile OTP system using firebase.
now i want to that API want to secure otherwise i want to hide that API.
how can i do that ?
any suggestions ???

2

This is really unrelated to Webflow. More to do with how to use Firebase on a html based site with no backend.

See => https://firebase.google.com/docs/projects/api-keys