Clerk

API

Authentication and user management with prebuilt sign-in UI

Price: Free tier, then paid
Access: Secret API key

About

Hosted authentication and user management with prebuilt sign-in components, organizations and enterprise SSO. Best suited to React and Next.js apps, with SDKs for many other stacks. Its Billing product charges through Stripe, in USD only.

What you can do with it

Add sign-up and sign-in with social login, passkeys and MFA via prebuilt components
Manage B2B organizations with roles, invitations and enterprise SSO
Sell subscription plans with a prebuilt pricing table and gate features by plan

Get started

Create an application in the Clerk Dashboard
Copy its secret key into CLERK_SECRET_KEY
In a web app, run npx clerk@latest init to add Clerk and its keys

Example

curl https://api.clerk.com/v1/users \
  -H "Authorization: Bearer $CLERK_SECRET_KEY"

Details

Hosting: Hosted service
Available in: Worldwide
Official SDKs: JavaScript/TypeScript, Python, Go, Java, Ruby, PHP, C#, Swift, Kotlin
MCP server: None
Works with: Stripe