Clerk

Clerk sells developer-facing authentication and user management infrastructure. Its core offering is a set of drop-in UI components — including <SignUp/>, <SignIn/>, <UserButton/>, <UserProfile/> and <Waitlist/> — plus SDKs and APIs that let application teams add sign-up, sign-in, profile management, session handling and account security to an application without building the underlying flows themselves. Components can be styled with any CSS library and deployed on the customer's own domain.

Beyond authentication, Clerk offers multi-tenancy features aimed at B2B SaaS: organizations as shared accounts, an organization switcher and profile components, custom roles and permissions, invitations, verified email domains and auto-join. A billing product lets developers define subscription plans, display pricing tables, unify user and subscription data and gate access to content without writing payment code or handling webhooks; the billing work is built on a partnership with Stripe integrating Stripe Billing. Additional capabilities include multifactor authentication, social sign-on with more than 20 providers, magic links, email and SMS one-time passcodes, passwords with breach detection, bot detection, fraud and abuse prevention (blocking disposable email domains and "+" subaddresses), session lifecycle management with device monitoring and revocation, and end-user API keys.

The company also targets AI-assisted development workflows, offering a Clerk CLI for agents to configure Clerk from the terminal and a published SKILL.md file for coding agents.

Business model

Clerk sells its authentication, user management, organization and billing infrastructure as a hosted developer platform consumed via SDKs, prebuilt UI components and backend APIs, configured through the Clerk Dashboard.

Usage-based subscription pricing with a free tier covering the first 50,000 monthly retained users and 100 monthly retained organizations, with no credit card required to start.

Traction

Clerk reported managing more than 16 million end-users and facilitating over one new sign-up per second at the time of its Series B, after surpassing one million managed users around its Series A in March 2023. Cumulative disclosed venture funding spans a $4M seed, $15M Series A, $30M Series B and $50M Series C.

Latest developments

Clerk announced a $50 million Series C in October 2025, with stated plans to accelerate its product roadmap, expand engineering, sales and customer success teams, and scale infrastructure. Recent product direction includes subscription billing components, end-user API keys, and agent-oriented tooling such as the Clerk CLI and a published SKILL.md integration file.