How it works
Clerk supplies drop-in components such as SignIn, SignUp, UserButton and UserProfile, plus hooks and server helpers for Next.js, React, React Router, Astro, Expo and native iOS and Android. Behind them sit passwords, magic links, email and SMS codes, social providers, passkeys, MFA, and organisations with roles and invitations for B2B apps. A dashboard lists every user and session, and bot protection, leaked-password checks and device management come built in.
Sessions pair a long-lived cookie held by Clerk's sign-in API with a short-lived JWT, lasting about a minute, that the SDK refreshes in the background, so revoking a session takes effect almost at once. User records live on Clerk's servers; apps that need users in their own database copy them over with webhooks. Clerk tokens can also be accepted by Supabase and other backends.
Billing counts monthly retained users: a person counts only once they come back at least a day after signing up, so sign-ups that never return cost nothing. Passkeys, MFA and removing Clerk branding need the Pro plan.
Clerk pros and cons
Pros
- Polished sign-in, profile and organisation screens in minutes
- Close Next.js integration, including middleware and server components
- Passkeys, MFA, social login and B2B organisations in one service
- Free plan covers 50,000 monthly retained users per app
Cons
- User data lives with Clerk, so your own database needs webhook syncing
- Passkeys, MFA and removing branding need a paid plan
- Costs grow per user past the free allowance
- Centred on JavaScript frameworks; other stacks get less support
When to use Clerk
Pick it when
- React or Next.js apps that want finished auth screens quickly
- B2B products that need organisations, roles and invitations
- Small teams that would rather not build account management
Skip it when
- Users must stay in your own database for legal or design reasons
- A backend platform such as Supabase or Firebase already covers sign-in
Clerk pricing
Free tier
Free for up to 50,000 monthly retained users per app. Pro from $25 a month ($20 billed yearly), then about $0.02 per extra user; SMS codes cost about $0.01 each in the US and Canada.
Clerk pricing page (opens in a new tab)Approximate, checked September 2026.What the other tools cost
Clerk vs the alternatives
Related terms
More in Auth and identity
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