Authentication providers bill on monthly active users (MAU), so the two numbers that matter are the size of the free tier and the rate beyond it. Here is how Auth0, Clerk and AWS Cognito (plus Supabase) compare. Figures are a June 2026 snapshot.
Estimate — verify with each vendor. Advanced features (enterprise SSO, advanced MFA, B2B orgs) are paid add-ons; confirm on each pricing page.
The answer first
| Provider | Free MAU tier | Paid per-MAU | Best for |
|---|---|---|---|
| Auth0 | 25,000 | sales-led / feature-gated | Enterprise SSO, compliance |
| Clerk | 10,000 | ~$0.02 + small base | React/Next.js consumer apps |
| AWS Cognito | 50,000 | ~$0.0055 | Cheapest at scale, AWS-native |
| Supabase Auth | 50,000 | ~$0.00325 | Teams already on Supabase |
See the full authentication comparison and the Auth0 vs Clerk matchup.
What it costs as you grow
Estimate cost as base + per-MAU × max(0, MAU − free tier). Try your numbers in the auth cost calculator. A few reference points:
| MAU | Auth0 | Clerk | Cognito |
|---|---|---|---|
| 8,000 | free | free | free |
| 20,000 | free | ~$25 + ~$200 | free |
| 60,000 | get a quote | ~$25 + ~$1,000 | ~$55 |
At 60,000 MAU, Cognito’s ~$0.0055 rate makes it dramatically cheaper than Clerk’s ~$0.02 — but Clerk ships prebuilt UI you would otherwise build yourself.
Cheapest isn’t the whole story
- Auth0 wins on enterprise SSO, compliance and its 25,000 free MAU, but paid plans escalate fast.
- Clerk wins on developer experience and prebuilt UI; the per-MAU rate is transparent and predictable.
- Cognito wins on raw price at scale and AWS integration; the trade-off is a weaker DX.
- Supabase Auth is the cheapest incremental rate if you are already building on Supabase.
Sources and accuracy
Rates are snapshots of each vendor’s public pricing page captured in June 2026. Auth0 paid tiers are sales-led, so we do not fabricate a per-MAU number for it. Estimates only — verify before relying on them. See our methodology.