Clerk is an authentication and user management platform that gives web and mobile apps ready-made sign-in, sign-up and account screens, plus the backend APIs to manage users, sessions and organizations.
Instead of building login flows, password resets, session handling and multi-factor authentication by hand, developers drop Clerk's components into their app and configure the rest from a dashboard. It is especially popular in the React and Next.js ecosystem, where its SDK integrates with middleware and server components.
Key features
- Prebuilt, customizable components for sign-in, sign-up, user profile and organization switching
- Email, SMS, social login, passkeys and multi-factor authentication (MFA on paid plans)
- Enterprise SSO and directory sync connections for B2B apps
- Organizations with roles, custom permissions and invitations for multi-tenant SaaS
- Official SDKs for Next.js, React, Remix, Astro, Expo and other frameworks, plus a backend API
- Clerk Billing for subscriptions on top of Stripe
- Bot protection and fraud prevention, including the newer Clerk Protect
Who it's for
Clerk suits startup and SaaS teams on modern JavaScript stacks that want production-grade auth without a dedicated identity engineer. It also fits B2B products that need organizations, roles and enterprise SSO.
Common use cases
- Adding login and user accounts to a Next.js or React app
- Building multi-tenant B2B SaaS with teams and roles
- Offering enterprise customers SAML/OIDC single sign-on
- Charging users for subscriptions with Clerk Billing
Pricing
Clerk's pricing page lists three self-serve plans:
- Hobby: $0 per month, with up to 50,000 monthly retained users (MRUs) per app.
- Pro: $25 per month ($20 billed annually). It includes 50,000 MRUs per app, then $0.02 per additional MRU, and adds MFA, removal of Clerk branding and one SSO connection.
- Business: $300 per month ($250 billed annually). It adds 10 dashboard seats, a SOC 2 report and enhanced roles.
Add-ons such as enhanced organizations are billed separately, and Clerk Billing charges 0.7% of billing volume on top of Stripe fees.
Alternatives
- SuperTokens: open-source auth you can self-host or use as a managed service
- Supabase: Postgres backend with built-in authentication
- Auth0: Okta's enterprise identity platform
FAQ
Is Clerk free?
Yes. Clerk's Hobby plan costs $0 and covers up to 50,000 monthly retained users per app.
What is Clerk used for?
Clerk is used to add sign-in, user accounts, MFA, SSO and team management to web and mobile apps without building auth yourself.
Clerk vs Auth0: which is better?
Clerk focuses on developer experience with prebuilt React components and simple pricing, while Auth0 offers a broader enterprise identity suite. Many startups pick Clerk for speed and Auth0 for complex enterprise requirements.
Does Clerk work with the Next.js App Router?
Yes. Clerk's Next.js SDK supports the App Router, middleware and server components.
Does Clerk support enterprise SSO?
Yes. Paid plans include SAML and OIDC SSO connections, with extra connections available as add-ons.
Can I self-host Clerk?
No. Clerk is a hosted service; if you need self-hosting, look at open-source options like SuperTokens.