Hey there! Let's break down your questions about Firebase Authentication (covering email/password and Google sign-in) clearly and straightforwardly:

Service Status #

Firebase Authentication is a stable, widely relied-on core service from Firebase. Both email/password sign-in and Google sign-in are fully supported and operational across most regions globally. Unless you're working in an area with specific regulatory restrictions that block Firebase services, you can count on these authentication methods to work consistently day-to-day.

Free Eligibility #

Great news—both email/password and Google sign-in are completely free to use under Firebase's Spark (Free) plan, with no mandatory upgrade required to get started. Here's the key detail on free usage:

• The free plan includes a monthly quota of 100,000 authentication operations (this covers user sign-ups, sign-ins, token validations, and other core auth-related actions). This quota is more than sufficient for personal projects, small-scale apps, or testing environments.

Connection/Concurrency Limits #

Firebase Authentication doesn't enforce hard, explicit limits on concurrent connections specifically for sign-in flows. But there are a few practical notes to keep in mind:

• While Auth itself doesn't cap concurrent logins, your overall Firebase project (on the free plan) does have limits on linked services like Real-Time Database concurrent connections. That said, this won't impact pure authentication requests as long as you stay within the 100k monthly operation quota.
• If you exceed the 100k monthly auth operations, your project will automatically switch to pay-as-you-go billing for the excess usage—your auth service won't be interrupted immediately. The pricing for excess operations is transparent and can be reviewed directly in your Firebase Console's pricing section.
• For Google sign-in specifically, Google's underlying OAuth 2.0 system has request rate limits, but these are set high enough that normal, non-abusive usage will never trigger them.

内容的提问来源于stack exchange，提问作者Dhruvam Sharma