Authentication · decision tool

Firebase Auth vs Supabase Auth — for your app, not in general

Firebase Auth or Supabase Auth? Set your usage, budget and constraints; the verdict, monthly cost and risks update live from verified pricing.

Prices verified 2026-07-15 against official pricing pages · fit weights are our estimates (see methodology) · share the URL to share your configuration

As of Jul 2026, with 5,000 monthly active users, a $50 budget for this slot, Supabase Auth ranks first for these inputs at 94% fit and a StackSays-estimated $0/month (Firebase Auth: 90% fit, $0/month). Fit weights are our estimates; prices trace to official pages. Change any input below and the verdict recomputes.

Your situation

The verdict updates as you move these.

Monthly active usersusers who actually sign in each month — the billing metric for most providersBudget for this slot ($/mo)what you'd accept paying for the auth provider layerTeam size1 = solo; bundled platforms save glue time for small teams

Narrow pick — the runner-up is close

Supabase Authfit 94% · est $0/mo

The cheapest managed auth at scale — if you're on Supabase anyway

vs Firebase Auth: fit 94% against 90%, est $0 against $0 per month

Supabase Authfit 94%

$0/mo

Firebase Authfit 90%

$0/mo

Comparing 2 tools head-to-head. Open the full field (7 options) →

The decision, in plain words

For a solo builder at 5,000 monthly active users and a $50.00/mo budget for the auth provider slot, Supabase Auth leads at 94% fit and $0/mo. The two rules doing the work: budget fit (Runs free at your usage — $0 vs your $50/mo budget); free-tier runway (Your usage fits the free tier today (50,000 MAU on the Supabase free plan)).

Firebase Auth runs close (90% fit, $0/mo). It takes the lead if runs free at your usage — $0 vs your $50/mo budget matters more to you than the current weights assume.

Generated from the calculation above — every number traces to the sourced data; nothing here is written by an AI making things up.

Why Supabase Auth scores 94%

Budget fit (weight 30, our estimate) — Runs free at your usage — $0 vs your $50/mo budget+30

Batteries included (weight 12, our estimate) — Bundles enterprise SSO — fewer services to glue at team size 1+4

Exit cost (weight 4, our estimate) — Users live in YOUR database — switching providers never holds your users hostage+4

Ecosystem maturity (weight 8, our estimate) — established — our estimate from ecosystem age, docs and hiring pool+8

Free-tier runway (weight 10, our estimate) — Your usage fits the free tier today (50,000 MAU on the Supabase free plan)+10

Total (lines sum exactly)56

Possible range −64…+64 (sum of active rule weights) · fit % = (total + max) / (2 × max)(56 + 64) / 128 = 94%

How the $0/mo estimate is calculated

Your usage fits Supabase Auth's free tier (50,000 MAU on the Supabase free plan) — the estimate is $0.

What could change this verdict

No single input change within the tested range changes the winner.

Cost risk

Estimated now (StackSays estimate, not your final bill)$0/mo · Free tier

Free-tier statusOn the free tier (50,000 MAU on the Supabase free plan)

Next known billing thresholdFree tier caps at 50,000 mau — beyond that you change plans

Official prices verified 2026-07-15; calculation is deterministic code over those prices.

At a glance

Tool	Free tier	Paid entry	Verified
Supabase Auth	50,000 MAU on the Supabase free plan	Pro (platform) $25/mo	2026-07-15
Firebase Auth	50,000 MAU at no charge	—	2026-07-15

Where did you land?anonymous, one click

Data sources

Tool	Source	Verified
Supabase Auth	Supabase pricing page	2026-07-15
Firebase Auth	Firebase pricing page	2026-07-15

A monitor re-checks these pages for changes; when a vendor moves a price, the date updates and every verdict recomputes.

Keep deciding