Clerk vs Auth0 vs Supabase Auth: what sign-in costs as your user base grows
Stack Founder HQ · Updated 18 October 2026 · Auth, email and analytics · How we write
Authentication is easy to start and expensive to change, because every user's account lives with the provider you pick. Clerk, Auth0 and Supabase Auth take different approaches. Clerk is a developer-focused service with prebuilt sign-in components. Auth0, owned by Okta, is an established identity platform with enterprise features. Supabase Auth comes bundled with the Supabase database platform. They also count users differently, and that affects your bill.
*Prices checked on 18 October 2026 on clerk.com/pricing, auth0.com/pricing and supabase.com/pricing. US dollars. Auth0 figures are for its B2C plans.*
How each service counts users
- Clerk charges by monthly retained users (MRU). According to Clerk, a user counts as retained when they come back 24 hours or more after signing up. People who sign up and never return don't count.
- Auth0 charges by monthly active users (MAU): users who log in during the month.
- Supabase also uses monthly active users for Auth.
Free plans
| Clerk Hobby | Auth0 Free | Supabase Free | |
|---|---|---|---|
| Users included | 50,000 MRU per app | Up to 25,000 MAU | 50,000 MAU |
| Notable inclusions | Prebuilt sign-up, sign-in and profile UIs; custom domain; up to 3 dashboard seats | Passwordless, unlimited social connections, 5 organisations, basic attack protection, 1 custom domain | Auth alongside the Supabase database, storage and functions |
| Notable limits | Fixed 7-day session lifetime; MFA is a Pro feature; Clerk branding shown | Community support; "Pro" MFA and role-based access per organisation are on paid plans | Free projects pause after a week of inactivity |
All three free plans are enough to launch a real product. The limits that tend to push people onto a paid plan are multi-factor authentication (Clerk) and project pausing (Supabase).
Paid plans
Clerk Pro costs $25 a month, or $20 a month billed annually. It includes 50,000 MRU per app, then $0.02 per MRU (with volume discounts at higher numbers). Pro adds MFA, removal of Clerk branding, custom session lifetimes and one enterprise SSO connection (additional connections are $75 a month each). Clerk Business is $250 a month billed annually, adding SOC 2 reports, more dashboard seats and priority support.
Auth0 Essentials starts at $35 a month for up to 500 MAU, adding higher limits, MFA, role-based access control and separate production and development environments. Auth0 Professional starts at $240 a month for up to 500 MAU, adding features such as using your existing user database for logins and enhanced attack protection. Prices rise with the number of users. Use the slider on Auth0's pricing page to check the cost for your expected user numbers.
Supabase Pro costs $25 a month and includes 100,000 MAU, then $0.00325 per MAU. The same $25 also covers your database, file storage and functions within Pro's quotas.
Worked examples
These use the published prices above. Auth0's paid prices above 500 MAU aren't listed as fixed figures, so check its calculator for those.
A consumer app with 10,000 active users a month:
- Clerk: $0 on Hobby, or $25 a month on Pro if you need MFA or want to remove the branding.
- Auth0: $0 on Free, which allows up to 25,000 MAU.
- Supabase: $0 on Free, though a production app is usually on Pro ($25) to avoid pausing and to get backups. That $25 also covers the database.
A consumer app with 80,000 active (or retained) users a month:
- Clerk Pro: 50,000 included, plus 30,000 × $0.02 = $600, plus $25, so about $625 a month (or about $620 with annual billing).
- Supabase Pro: within the 100,000 MAU included, so $25 a month, plus any database or other usage over the quotas.
- Auth0: above the free 25,000 MAU, so a paid plan, priced using Auth0's calculator.
At larger user numbers, Supabase Auth is much cheaper per user. Clerk's MRU counting partly offsets this for apps where many people sign up and never come back, because those users don't count.
Features and developer experience
- Clerk is built around ready-made UI components and hooks, especially for React and Next.js. You can have polished sign-in, sign-up, user profile and organisation management screens working in very little time.
- Auth0 has the widest range of enterprise features: many identity providers, SAML and enterprise connections, extensibility through Actions, and compliance features. It suits B2B products that sell to larger companies, though enterprise features often need higher plans.
- Supabase Auth integrates with Postgres row-level security. A user's ID is available inside database policies, so access control can live in the database itself. Its UI options are more basic, so expect to build more of the screens yourself.
Lock-in and migration
Moving users between providers is hard, mainly because of password hashes. If the new provider can import your existing hashes, users can keep their passwords. If not, everyone has to reset their password, or you need a gradual migration that moves each user when they next log in. Before choosing, check each provider's documentation on exporting users and password hashes. Supabase stores users in a table in your own Postgres database, which makes them comparatively easy to access.
Which to choose
- Clerk if you want the fastest polished front-end experience, especially on Next.js, and your number of retained users will stay moderate.
- Auth0 if you are selling to businesses that need enterprise SSO and compliance features, and the price per user fits your margins.
- Supabase Auth if you already use, or plan to use, Supabase for your database, or you expect large numbers of users on a tight budget.