At 10,000 monthly users with multi-factor login (MFA), Clerk Pro and Supabase Pro each cost $25 a month, Auth0 B2C Essentials costs $700, and Better Auth costs $0 in fees because you run it yourself. Without MFA, Clerk, Auth0, and Supabase all have free tiers that cover 10,000 users, and the gap only opens once you need MFA, enterprise SSO, or pass 50,000 users.
Who this is for: founders and product leads picking a login provider for a new SaaS or app, or checking whether their current bill still makes sense. Who should look elsewhere: teams that must keep every credential inside their own network for compliance (Better Auth on your own database is the only one of the four that does that), and internal tools where staff already sign in with Google or Microsoft. Our guide on when to build auth and when to buy it covers that first decision.
How we checked
We read each vendor’s own pricing page on 2026-10-13 and did the math ourselves. All prices are US list prices in USD, billed monthly, software only. We didn’t get sales quotes, so anything marked “sales quote” means the vendor doesn’t publish a price at that size.
Most pages that rank for “Clerk vs Auth0 pricing” are out of date. Several still say Clerk’s free tier is 10,000 users and Auth0’s is 7,500. Clerk moved its free tier to 50,000 retained users, and Auth0’s free tier is now 25,000 monthly active users. The comparisons we read also skip Better Auth’s paid infrastructure plan and Supabase’s per-user SSO fee. Both are below.
The four bills side by side
Each provider counts users differently, and that changes the bill more than the headline price.
- Clerk bills Monthly Retained Users. “A Monthly Retained User is a user who visits your app in a given month at least one day after signing up” (Clerk pricing). Someone who signs up and never returns after day one is never billed.
- Auth0 bills Monthly Active Users: “Any non-internal (non-employee) user that authenticated during a given month for a given tenant” (Auth0 pricing).
- Supabase bills “the number of distinct users who sign in or refresh their token during the billing cycle” (Supabase docs). A token refresh counts, so a user who leaves a tab open counts too.
- Better Auth is an MIT-licensed library (GitHub). “The Better Auth framework is free and open source” (Better Auth pricing). There’s no per-user fee at any size.
Monthly cost by user count
| Scenario | Clerk | Auth0 (B2C) | Supabase Auth | Better Auth |
|---|---|---|---|---|
| 1,000 users, no MFA | $0 (Hobby) | $0 (Free) | $0 (Free, pauses when idle) or $25 (Pro) | $0 + hosting |
| 10,000 users, no MFA | $0 (Hobby) | $0 (Free) | $0 (Free) or $25 (Pro) | $0 + hosting |
| 1,000 users, with MFA | $25 (Pro) | $70 (Essentials) | $25 (Pro) | $0 + hosting |
| 10,000 users, with MFA | $25 (Pro) | $700 (Essentials) | $25 (Pro) | $0 + hosting |
| 100,000 users, with MFA | $1,025 (Pro) | Sales quote | $25 (Pro) | $0 + hosting |
Checked 2026-10-13. Monthly billing, US list prices, software only. Sources: Clerk, Auth0, Supabase, Better Auth. Math by Dawloom.
How we got the less obvious cells:
- Clerk at 100,000: Pro is $25 a month and includes 50,000 retained users per app. Users 50,001 to 100,000 cost $0.02 each. So $25 + 50,000 × $0.02 = $1,025. Billed yearly, the base drops to $20 (Clerk pricing, checked 2026-10-13).
- Auth0 at 10,000: B2C Essentials lists $700 a month at 10,000 users. “Pricing is available only at the listed MAU tiers. If your usage falls between tiers, you are billed at the next tier up” (Auth0 pricing, checked 2026-10-13). So 10,001 users bills at the 20,000 tier, $1,400.
- Auth0 at 100,000: the highest self-serve B2C Essentials tier is 50,000 users at $3,500 a month. Above that the page says contact sales.
- Supabase at 100,000: Pro includes “100,000 included, then $0.00325 per MAU” (Supabase pricing, checked 2026-10-13). So 100,000 users stays at $25. Pro also includes “$10/month in compute credits that cover one project on Micro compute”. A bigger database costs more, and that cost is your database, not auth.
- Supabase Free: “Free projects are paused after 1 week of inactivity. Limit of 2 active projects” (same page). Fine for a prototype, risky for a product.
The chart shows why “which is cheapest” depends on your size. Under 25,000 users with no MFA, Auth0’s free plan is generous. Once you need MFA, Auth0 is the most expensive of the four by a wide margin, and the steps are steep: going from 10,000 to 10,001 users doubles the bill.
What MFA costs on each
MFA costs nothing extra on Supabase (any plan) or Better Auth, needs Clerk Pro ($25), and needs at least Auth0 Essentials ($35 at 500 users). Details from each pricing page:
- Clerk: the MFA row reads Hobby “No”, Pro “Yes”, Business “Yes”. SMS codes cost “$0.01 per SMS” in the US and Canada (Clerk pricing).
- Auth0: the Free plan has no MFA. Essentials includes “Pro Multi-Factor Authentication”, and Professional includes “Enterprise Multi-Factor Authentication” (Auth0 pricing). The page is inconsistent on whether Enterprise MFA is included or a $100 add-on on B2C Essentials, so ask before you buy.
- Supabase: “Basic MFA” is included on every plan, Free too. Phone MFA is “$75 per month for first project, then $10 per month per additional projects” on Pro (Supabase pricing).
- Better Auth: the two-factor plugin supports authenticator apps (TOTP), one-time codes by email or SMS, and backup codes (Better Auth docs). You pay your own email and SMS provider.
B2B: one enterprise customer wants SAML SSO
One SAML SSO connection at 10,000 users costs $25 a month on Clerk Pro, about $25 on Supabase Pro, $0 plus hosting on Better Auth, and $2,100 on Auth0, which needs a B2B plan. That’s the case when one enterprise customer asks for login through Okta or Microsoft Entra. Checked 2026-10-13:
| Provider | Plan you need | Monthly cost | Extra connections |
|---|---|---|---|
| Clerk | Pro: “1 SSO connection included” | $25 | $75 a month each for 2 to 15, $60 for 16 to 100 |
| Auth0 | B2B Essentials (B2C paid plans list enterprise connections as “Not available”) | $2,100 | 3 included, then $100 a month each, 30 at most |
| Supabase | Pro: “50 included, then $0.015 per MAU” | $25 + $0.015 per SSO user above 50 | Billed per SSO user, not per connection |
| Better Auth | Free SSO plugin, SAML and OIDC | $0 + hosting | Optional dashboard plan: $20 a month, “1 connection, then $50/month per connection” |
Sources: Clerk, Auth0, Supabase, Better Auth SSO plugin, Better Auth pricing. All checked 2026-10-13.
Two details worth knowing. Auth0’s Free plan lists 1 enterprise connection, so a small B2B app without MFA can start at $0. And with Supabase, an enterprise customer with 500 staff on SSO adds 450 × $0.015 = $6.75 a month. That’s our math from the listed rate.
Clerk also bills B2B organizations separately. The free tier covers 100 retained organizations with “Up to 20 members per Organization”. Past that you need the B2B add-on at $100 a month (Clerk pricing).
What “$0 plus hosting” means for Better Auth
Better Auth runs inside your own backend and stores users in your own database. There’s no vendor bill per user, but you take on what a vendor would do:
- Storage and uptime. The user table sits in your database. If the app already has Postgres, the extra cost for 10,000 users is close to nothing.
- Email and SMS. You plug in your own provider for verification and reset emails.
- Security work. Rate limits, breach response, and keeping the library updated are on your team. Our auth build-or-buy guide covers what owning credentials really costs.
- Optional paid layer. Better Auth’s infrastructure plan adds a dashboard, audit logs, and security detections. Pro is $20 a month, “For production teams running auth in the critical path”, with “20,000 audit logs / month” (Better Auth pricing, checked 2026-10-13). The library keeps working without it.
Supabase sits in between. Auth is bundled with a hosted Postgres database, so the $25 Pro plan also pays for your database. If you’d use Supabase as your database anyway, auth is close to free. Our post on why we default to Postgres explains why that pairing is common.
Which one to pick
- Pick Clerk for a React or Next.js app that wants prebuilt sign-in screens, MFA, and one SSO connection for $25 a month. Watch the bill above 50,000 retained users.
- Pick Auth0 when you need its enterprise features, such as many SSO connections, or a buyer’s security team already knows it. Below 25,000 users without MFA it’s free. With MFA it’s the priciest of the four at every size we checked.
- Pick Supabase Auth when Supabase is already your database. 100,000 users with MFA for $25 is hard to beat.
- Pick Better Auth when you want no per-user fee and no vendor holding your user table, and your team can own the security work. It fits best in a TypeScript backend you already run. See Go, Node, or Bun for your backend if that backend isn’t chosen yet.
If you’re building a SaaS and want sign-in, billing, and tenancy done once and done right, our AI SaaS and web development pages explain how we scope that. Our post on multi-tenant isolation models covers the tenancy side.
FAQ
Is Clerk cheaper than Auth0?
At most sizes, yes. With MFA at 10,000 users, Clerk Pro is $25 a month and Auth0 B2C Essentials is $700, both checked 2026-10-13. Without MFA, both are free at 10,000 users. Auth0’s free plan covers up to 25,000 monthly active users and Clerk’s Hobby plan covers 50,000 retained users.
How much does Auth0 cost for 10,000 users?
$0 on the Free plan if you don’t need MFA. $700 a month on B2C Essentials, $1,600 on B2C Professional, $2,100 on B2B Essentials, and $2,400 on B2B Professional, billed monthly. Yearly billing is “11× the monthly price” (Auth0 pricing, checked 2026-10-13).
Is Better Auth really free?
The library is MIT-licensed and has no per-user fee. You pay for the server and database it runs on, plus email and SMS. Better Auth also sells an optional infrastructure plan with a dashboard and audit logs, from $20 a month.
What counts as a monthly active user in Supabase?
Any distinct user who signs in or refreshes a token during the billing cycle, counted once per cycle. Pro and Team include 100,000, then $0.00325 per user (Supabase docs).
Does Clerk charge for users who sign up and never come back?
No. Clerk bills retained users, people who return at least one day after signing up. Clerk calls this “First Day Free” (Clerk pricing).