Add login to your app
Auth providers differ most in who counts as a billable user, what the free tier allows, and how much you must configure yourself. Use the table below to match your situation.
Facts checked 2026-10-23. Some links on this site may become affiliate links in future; see the disclosure. None are affiliate links today.
Which one fits you?
- Already using Supabase for your database? Use Supabase Auth; it is built in.
- Want prebuilt sign-in screens in a React or Next.js app with the least work? Look at Clerk.
- Want to own user data and avoid per-user fees, and you are on TypeScript? Look at Better Auth.
- Already on Google Cloud or Firestore? Firebase Authentication fits.
- Expecting enterprise customers with SSO requirements? Auth0 or Clerk Pro.
Our picks
You already use Supabase
Supabase
Why: Free plan includes 50,000 monthly active users; Pro is $25/month with 100,000.
Tradeoff: Free projects pause after 1 week of inactivity. Enable Row Level Security on every table you expose.
Source: supabase.com · checked 2026-10-23 · full entry
Prebuilt UI, fastest start
Clerk
Why: Hobby is free up to 50,000 monthly retained users per app; Pro is $25/month ($20 billed annually).
Tradeoff: MFA and removing Clerk branding need Pro.
Source: clerk.com · checked 2026-10-23 · full entry
Own your data, no per-user fees
Better Auth
Why: MIT-licensed TypeScript framework that runs inside your app.
Tradeoff: You run the database, secrets and security configuration.
Source: www.better-auth.com · checked 2026-10-23 · full entry
Google Cloud / Firebase stack
Firebase Authentication
Why: Part of Firebase with a no-cost Spark plan.
Tradeoff: Phone sign-in has separate limits; check the limits page.
Source: firebase.google.com · checked 2026-10-23 · full entry
Enterprise SSO expected
Auth0
Why: Free up to 25,000 MAUs; paid plans start at $35/month for 500 MAUs.
Tradeoff: Paid cost scales steeply with MAUs ($700/month at 10,000 on Essentials).
Source: auth0.com · checked 2026-10-23 · full entry
Common mistakes
Leaving the Site URL on localhost
Supabase defaults the Site URL to http://localhost:3000. It is used for email confirmations and password resets, so change it to your production URL.
Redirect URL not on the allow list
The redirectTo URL in your code should match the Redirect URLs list configured in Supabase.
Tables without Row Level Security
Supabase documents that a table in an exposed schema without RLS is readable and writable by any role with a grant on it.
Source: supabase.com/docs/guides/database/postgres/row-level-security
Assuming "active" means the same thing everywhere
Auth0 defines a monthly active user as any non-internal user who authenticated during a given month for a given tenant. Clerk counts monthly retained users, meaning someone who visits at least one day after signing up, and does not bill a user who never returns.
Source: clerk.com/pricing