Auth pricing · April 2026

Firebase Authentication Pricing: Free Tier, Phone Auth, and SMS Costs (2026)

Firebase Auth is free for almost all authentication methods. The only costs come from phone (SMS) verification — and they vary significantly by country.

Authentication Methods and Pricing

Auth MethodSpark planBlaze plan
Email / PasswordFree — 50,000 MAUFree — unlimited
Google Sign-InFree — 50,000 MAUFree — unlimited
Apple Sign-InFree — 50,000 MAUFree — unlimited
Facebook, GitHub, Twitter, MicrosoftFree — 50,000 MAUFree — unlimited
Anonymous AuthFree — unlimitedFree — unlimited
Email link (passwordless)Free — 50,000 MAUFree — unlimited
SAML / OIDC (enterprise SSO)Not available
Phone / SMS VerificationNot available

Phone Auth — Country-Based SMS Pricing

SMS verification rates vary significantly by country. The first 10,000 verifications per month are free (Blaze plan). Beyond that, you pay the per-country rate. This can be a meaningful cost for apps with global audiences.

CountryCodeRate per SMS (beyond free tier)Note
United StatesUSMost common use case
CanadaCA
IndiaINLow cost, high volume market
United KingdomGB~9× more than US
GermanyDE
AustraliaAU
BrazilBRWatch for unexpected costs
NigeriaNGMost expensive tier
UK/Europe cost example

An app sending 15,000 SMS verifications/month to UK phone numbers: (15,000 − 10,000 free) × $0.04 = $200/month in phone auth costs alone. A predominantly UK user base at modest scale can produce significant unexpected SMS bills.

What Counts as a Phone Verification?

Not every phone-number-related action triggers a billable SMS. Understanding what counts is essential for cost management.

Counts as billable
×
Initial phone number verification (new user signing up with phone)
×
SMS code re-send (if user requests a new code)
×
Phone number change (triggers new verification)
×
Multi-factor auth SMS sent for sign-in
Does NOT count
Returning user logging in with a cached credential on the same device
Silent verification via SafetyNet / Device Check (on supported devices)
Test phone numbers in the Firebase console (always free)

How to Reduce Phone Auth Costs

Enable App Check to block bot-triggered verifications
Bots and scrapers can trigger phone SMS verifications at scale, running up your bill. Firebase App Check (backed by reCAPTCHA v3 for web, SafetyNet/DeviceCheck for mobile) verifies that requests come from genuine users before sending SMS.
Implement rate limiting per phone number
Apply client-side or Cloud Functions-side rate limiting to prevent the same number from triggering multiple SMS sends within a short window. Firebase has built-in "Send another code" delays, but server-side limits add a second layer.
Use device-cached credentials
Once a user has verified their phone and is logged in, their credential is cached on the device. Subsequent sign-ins on the same device use the cached token — no SMS. Encourage users not to log out unnecessarily.
Use test phone numbers in development
Firebase allows you to configure test phone numbers in the console (Authentication → Sign-in method → Phone → "Phone numbers for testing"). These send no actual SMS and cost nothing. Always use them in development and CI.

Frequently Asked Questions

Email/password, social (Google, Apple, Facebook, GitHub, etc.), and anonymous authentication are all free at any scale on the Blaze plan. On the Spark plan, email and social auth are limited to 50,000 monthly active users — which is sufficient for most apps. Phone (SMS) authentication requires the Blaze plan and has a free tier of 10,000 verifications/month.
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