How can username and password per user be securely stored for access to external REST APIs?

Hi everyone,
I’m currently developing an app for Monday.com that connects to an external REST API. Access to this API requires a username and password per user—not a global API key, but individual credentials for each app user.

My question is:
What is the recommended way to securely store and manage these credentials per user so they can be used within the app?

Is there a best practice or built-in method in Monday for handling sensitive data like this securely?

Any insights or guidance would be greatly appreciated.