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Best Firebase Auth alternatives (2026)

Firebase Authentication is free for most small apps, but the no-cost Spark plan caps email-link sign-in at 5 emails a day and password-reset emails at 150 a day, phone sign-in needs the pay-as-you-go Blaze plan, and past 50,000 monthly active users (MAU) with Identity Platform you pay $0.0055 per user (SAML and OIDC sign-ins cost $0.015 each after the first 50). Your users also live in Google’s proprietary user store. These alternatives cover hosted auth with bigger free tiers (Clerk, WorkOS, Kinde, Stytch), auth bundled with a Postgres backend (Supabase Auth), open-source libraries that keep users in your own database (Better Auth, Auth.js) and SSO-first services (Auth0, Descope). Ranked by our evidence-based score, with Firebase Authentication shown last for reference.

Editorial picks for this use case. See each tool page for its score breakdown. Last updated 2026-10-25.

#1
C
Clerk
User management and authentication
Verified
87
/ 100
 #2
B
Better Auth open source
Open-source TypeScript auth framework
Verified
86
/ 100
 #3
S
Supabase Auth open source
Auth built into your Supabase Postgres, with 50,000 free MAU
Verified
85
/ 100
 #4
W
WorkOS
Enterprise-ready auth and SSO
Verified
78
/ 100
 #5
K
Kinde
Auth, B2B organizations and billing in one, with 10,500 free MAU
Verified
76
/ 100
 #6
A
Auth.js (NextAuth.js) open source
The classic open-source auth library for Next.js, now part of Better Auth
Verified
73
/ 100
 #7
A
Auth0
Identity platform by Okta
Verified
70
/ 100
 #8
D
Descope
Drag-and-drop auth flows, plus MCP and AI-agent auth
Verified
70
/ 100
 #9
S
Stytch
Authentication and fraud prevention
Verified
68
/ 100
 #10
F
Firebase Authentication
Google's drop-in auth for web and mobile apps
Verified
74
/ 100

The short version

Clerk (87) is our top-ranked auth and the easiest swap for a Next.js or React web app: 50,000 free monthly retained users per app, prebuilt sign-in components, and a migration script with a firebase transformer that keeps Firebase passwords working. Better Auth (86) is the pick if you want users in your own database with no per-user fees. Supabase Auth (85) is the natural move if you are leaving Firestore for Postgres too, and Supabase publishes a Firebase Auth migration tool. WorkOS (78) has the biggest hosted free tier (AuthKit free up to 1 million users) and a migrations CLI that imports Firebase’s scrypt password hashes. Kinde (76) bundles organizations and billing, Auth.js (73) is the classic free Next.js library (now part of Better Auth), Auth0 (70) and Descope (70) suit enterprise SSO, and Stytch (68) is pay as you go. Firebase Authentication scores 74, shown last for reference: it is still a strong choice for mobile and Flutter apps.

Why people look for a Firebase Auth alternative

Spark-plan email quotas: Firebase’s limits page (read Oct 22, 2026) caps email-link sign-in at 5 emails a day on the no-cost Spark plan (“add a billing instrument to go beyond 5”), password-reset emails at 150 a day and verification emails at 1,000 a day. On the Blaze plan those rise to 25,000, 10,000 and 100,000. With Identity Platform, Spark also caps you at 3,000 daily active users. Phone and SMS: phone sign-in and SMS multi-factor are billed per message, and only on Blaze. Per-user pricing past 50,000: with Identity Platform, email, phone, anonymous and social users are free to 50,000 MAU, then $0.0055 each to 100,000, $0.0046 to 1 million and $0.0032 to 10 million. SAML and OIDC users are free only for the first 50, then $0.015 each, so 2,000 enterprise SSO users is about $29/mo. Lock-in: users sit in Google’s proprietary store with a modified scrypt password hash, and Firebase Auth is easiest with the rest of Firebase. Teams moving to Postgres or a non-Google stack often move auth at the same time.

Quick picks by need

Fastest drop-in for Next.js or React: Clerk (Pro $25/mo, or $20/mo billed annually). Moving from Firestore to Postgres: Supabase Auth, since users land in your own auth.users table. Own your users, no per-user fees: Better Auth (MIT) or Auth.js (ISC) for an existing NextAuth app. Biggest hosted free tier: WorkOS AuthKit, free up to 1 million users. Organizations plus billing on a budget: Kinde (Free 10,500 MAU). Enterprise SSO: WorkOS ($125 per connection a month, cheaper in volume), Auth0 (Free includes 1 enterprise connection) or Descope (3 SSO connections free). Mobile or Flutter app on Google Cloud: stay on Firebase Authentication.

Cost at 10,000 and 100,000 MAU

Computed from each vendor’s published rates (monthly billing unless noted). At 10,000 MAU: Firebase Authentication is $0 (plus SMS if you use phone sign-in), and so are Clerk, Supabase, WorkOS, Kinde, Stytch and Auth0 on their free plans; Better Auth and Auth.js have no per-user fees. Descope’s free plan stops at 7,500 MAU, so you need Pro, from $249/mo billed annually. At 100,000 MAU: Firebase with Identity Platform is 50,000 × $0.0055 = $275/mo. Supabase Pro is $25/mo with 100,000 MAU included, WorkOS is $0, and Better Auth and Auth.js are $0 per user. Clerk Pro is $25 + 50,000 × $0.02 = about $1,025/mo, and Kinde Pro is $25 + 89,500 × $0.0175 = about $1,591/mo. Auth0 Free stops at 25,000 MAU and its calculator shows “Get in touch” for most plans past 30,000, so expect a sales quote. Stytch doesn’t publish its per-MAU rate past 10,000, so we don’t quote a figure. Firebase is cheaper than most hosted rivals at this size; the reasons to move are the quotas, SSO pricing and lock-in, not the per-user rate.

Moving your users off Firebase Auth

Export the users: firebase auth:export users.json (Firebase CLI) writes every account to JSON or CSV, including the password hash and salt. Get the hash parameters: in the Firebase console under Authentication, Users, the three-dot menu shows “Password hash parameters”: base64_signer_key, base64_salt_separator, rounds and mem_cost. Most projects use Firebase’s modified SCRYPT, and the importer needs these values to verify old passwords, so treat them as secrets. Import on the target: Clerk’s migration script takes --transformer firebase with --firebase-signer-key and --firebase-salt-separator; WorkOS’s migrations CLI (npx workos migrations export firebase) converts the export, scrypt hashes included, into a migration package; Supabase’s firebase-to-supabase tool imports users into auth.users, and its repo has a middleware option that checks each Firebase password on first sign-in and stores a new hash. Social-login users reconnect the same provider, and active sessions end at cutover, so plan a sign-in prompt.

When to stay on Firebase Auth

Stay if you ship a mobile or Flutter app, already use Firestore, Cloud Functions or other Google Cloud services, or are under 50,000 MAU on the Blaze plan, where the email quotas are generous. Its per-user price past 50,000 ($0.0055, falling to $0.0046 past 100,000) is lower than Clerk’s or Kinde’s. Move when you need prebuilt web UI and organizations (Clerk, Kinde), SSO for many customers without $0.015 per user (WorkOS), or users in your own Postgres database (Supabase Auth, Better Auth).

Side-by-side comparison

ToolScoreFree tierPricingBest for
Clerk87Yes: 50,000 monthly retained users per appPro $25/mo ($20 annual), then $0.02/MRU over 50KThe fastest auth for Next.js/React SaaS
Better Auth86Yes: MIT library free to self-host; Infrastructure Starter $0Library free; optional Infrastructure Pro $20/moOwning auth in your own database with no per-user fees
Supabase Auth85Yes: 50,000 monthly active users on the Supabase Free plan (free projects pause after 1 week of inactivity, 2 active projects max)Included in Supabase plans: Free $0 (50,000 MAU); Pro from $25/mo (100,000 MAU, then $0.00325 per MAU); Team from $599/mo; Enterprise custom. Advanced phone MFA, SAML SSO and leaked-password protection are paid featuresApps already on Supabase, or vibe-coded apps from Lovable and Bolt that need sign-in tied to row-level security
WorkOS78Yes: AuthKit free up to 1M MAUSSO/Directory Sync $125/connection/mo (volume discounts)SaaS that will sell to enterprises needing SSO/SCIM
Kinde76Yes: 10,500 MAU free forever, no credit card, including social login, MFA, organizations and custom domainFree $0 (10,500 MAU); Pro $25/mo (10,500 MAU included, then $0.0175 per extra MAU); Plus $75/mo (free enterprise SSO); Scale $250/mo; billing customers through Kinde adds 0.5–0.7% per transaction (0.7% Free/Pro, 0.6% Plus, 0.5% Scale), and those billed users' MAU is freeSaaS founders who want auth, orgs and subscription billing from one provider
Auth.js (NextAuth.js)73Yes: fully free and open source, no per-user feesFree (ISC open source); you host it and pay only for your own databaseExisting Next.js apps already on next-auth; new projects should look at Better Auth first
Auth070Yes: up to 25,000 MAUEssentials from $35/mo (B2C, 500 MAU) or $150/mo (B2B)Enterprise identity requirements and compliance
Descope70Yes: 7,500 MAU, 10 tenants and 3 SSO connections free forever, no overages (upgrade required past limits)Free Forever $0 (7,500 MAU, 10 tenants, 3 SSO connections, hard limits); Pro from $249/mo billed annually (10,000 MAU, then $0.05/MAU); Growth from $799/mo (25,000 MAU); Enterprise customB2B apps and MCP servers that need tenant SSO or agent auth without writing flows by hand
Stytch68Yes: 10,000 MAU, 5 SSO/SCIM connectionsUsage-based above free allowance; SSO/SCIM $125/connectionPasswordless and fraud-aware auth
Firebase Authentication74Yes: no-cost on the Spark plan; with Identity Platform free up to 50K MAU (Spark caps Identity Platform at 3,000 daily active users, and password-reset emails at 150/day)No-cost Spark plan; with Identity Platform, no-cost up to 50K MAU (50 MAU for SAML/OIDC), then Google Cloud pricing; phone verification SMS is Blaze (pay-as-you-go) only and billed per SMSMobile and Flutter apps, or projects already on Firebase and Google Cloud

FAQ

What is the best Firebase Auth alternatives in 2026?
Our top pick is Clerk (score 87/100): User management and authentication. Runners-up: Better Auth, Supabase Auth, WorkOS, Kinde, Auth.js (NextAuth.js), Auth0, Descope, Stytch, Firebase Authentication.
Is Clerk free?
Clerk free tier: Yes: 50,000 monthly retained users per app. Paid pricing: Pro $25/mo ($20 annual), then $0.02/MRU over 50K.
Is Better Auth free?
Better Auth free tier: Yes: MIT library free to self-host; Infrastructure Starter $0. Paid pricing: Library free; optional Infrastructure Pro $20/mo.
Is Supabase Auth free?
Supabase Auth free tier: Yes: 50,000 monthly active users on the Supabase Free plan (free projects pause after 1 week of inactivity, 2 active projects max). Paid pricing: Included in Supabase plans: Free $0 (50,000 MAU); Pro from $25/mo (100,000 MAU, then $0.00325 per MAU); Team from $599/mo; Enterprise custom. Advanced phone MFA, SAML SSO and leaked-password protection are paid features.
How are these tools ranked?
Each tool is scored out of 100 on fit, vibe-coder friendliness, output quality, pricing, ecosystem, momentum and code ownership, using desk research of official docs and pricing pages. Affiliate status never affects scores.
What is the best alternative to Firebase Authentication?
Clerk, at 87 in our ranking, for the fastest drop-in auth on the web, with a Firebase importer that keeps passwords working. Better Auth (86) if you want users in your own database with no per-user fees, Supabase Auth (85) if you are moving to Postgres, and WorkOS (78) for AuthKit free up to 1 million users.
Is Firebase Authentication free?
Mostly. It is no-cost on the Spark plan, and with Identity Platform free up to 50,000 MAU for email, social, phone and anonymous users. The Spark plan caps email-link sign-in at 5 emails a day and password resets at 150 a day, phone SMS is billed per message on Blaze only, and SAML or OIDC users cost $0.015 each after the first 50.
How much does Firebase Auth cost for 100,000 users?
About $275/mo with Identity Platform: the first 50,000 MAU are free and the next 50,000 cost $0.0055 each (Google Cloud pricing, read Oct 22, 2026). SMS and SAML/OIDC users are billed separately.
Can I migrate Firebase users without resetting passwords?
Yes. Export users with <code>firebase auth:export</code>, copy the password hash parameters from the Firebase console, and import with a tool that understands Firebase’s modified scrypt, such as Clerk’s migration script, the WorkOS migrations CLI or Supabase’s firebase-to-supabase tool.

Sources (checked Oct 22, 2026)

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