Clerk is a drop-in authentication and user-management API — sign-up/sign-in UI components, session handling, organizations and enterprise SSO, without building auth from scratch. Since February 2026 its free tier jumped to 50,000 users and its billing unit changed to Monthly Retained Users (MRUs) — a meaningfully different (and friendlier) metric than a raw MAU count.
| Plan | Price | Included |
|---|---|---|
| Free free tier | $0 | 50,000 MRU/mo, core auth (SAML, OIDC, SSO) |
| Pro | $25/mo (or $20/mo billed annually) | 50,000 MRU included, then ~$0.02/extra MRU (volume discounts) |
| Business | $300/mo | SOC2 compliance, team management |
| Enterprise | custom | HIPAA, dedicated support, custom SLAs |
Most auth providers bill on Monthly Active Users — anyone who logs in counts, including people who sign up once out of curiosity and never come back. Clerk's Monthly Retained User metric only counts someone once they return to your app at least 24 hours after their first session. That filters out throwaway signups, bot noise, and one-and-done trial accounts, so the number you're billed on tracks people who actually got value from your product — a materially cheaper bill than a same-size app on a pure per-MAU competitor, all else equal.
1. Sign up at clerk.com and create an application (pick your framework — Next.js, React, Remix, Expo, etc.).
2. Go to API Keys in the dashboard sidebar.
3. Copy the Publishable Key (safe for frontend code, starts with pk_) and the Secret Key (server-side only, starts with sk_, shown once — store it in your env vars).
4. Wrap your app with Clerk's provider component using those keys and drop in the pre-built <SignIn/>/<SignUp/> components.
Verify a session server-side:
Supabase Auth (see our Supabase guide) is bundled free with a Supabase project if you're already using it for your database — cheapest option if Postgres fits your stack. Auth0 and WorkOS lean more enterprise-first with pricier per-user rates at scale but deeper compliance tooling out of the box (see our Auth0 vs Clerk vs WorkOS comparison). Better Auth is a newer open-source, self-hosted option with no per-user billing at all if you're willing to run and maintain it yourself. Clerk sits in the middle: generous free tier, fastest to ship, MRU billing that's kinder than raw MAU.
Yes — up to 50,000 Monthly Retained Users with core authentication (SAML, OIDC, enterprise SSO) included, since the February 2026 tier change.
A user who returns to your app at least 24 hours after signing up. One-time signups that never come back don't count — a friendlier metric than raw MAU billing.
Sign up, create an application, then copy the Publishable Key and Secret Key from the API Keys page in your dashboard.
Clerk's free tier (50,000 MRUs) and $25/mo Pro entry point undercut Auth0 for small-to-mid apps. Auth0 and WorkOS tend to pull ahead only at enterprise scale with heavier compliance needs — see our full three-way comparison.
Not affiliated with Clerk. Prices are reference estimates — always verify on the official pricing page.