For the Love of the Developer: Announcing Clerk’s Series C

In application development, there are two universal truths: 1) Every application needs authentication, and 2) No developer wants to build authentication. 

Building customer-facing auth is particularly arduous—developers must interpret security protocols, debug session management edge cases, handle password breaches, and navigate compliance requirements, all while maintaining a delightful experience for potentially millions of users where any misstep damages both security and brand trust. Now, as AI agents increasingly need to authenticate and act on behalf of users, these challenges multiply exponentially.

Solving this requires mastery of both developer experience and user experience, and this intersection is exactly where Clerk excels. In the last two years, Clerk has become ubiquitous among developers. Their combination of technical excellence and customer love is why we’re thrilled to announce Clerk’s Series C round, led by Menlo Ventures with an investment through the Anthology Fund, a joint partnership between Anthropic and the firm. Brothers Colin and Braden Sidoti built Clerk from firsthand, authentic developer pain. They’ve reimagined authentication with a component-first approach that reduces implementation time from weeks to hours while improving conversion rates—and they’re building the identity infrastructure for an AI-native world.

Components > APIs 

Clerk recognized early that React components could deliver full-stack authentication functionality while offering far more flexibility and scalability and an overall improved builder experience. Developers simply drop <SignIn />, <SignUp />, and <UserProfile /> components into their applications. They handle OAuth, multi-factor authentication, session management, and enterprise compliance while staying completely on-brand.

The results are compelling: Over 95% of customers use all three core components, implementation time drops from weeks to hours, and conversion rates improve because users never leave the application domain.

AI Agents and Platform Expansion

Clerk’s stronghold position among developers puts them in the driver’s seat for an AI-driven future. As autonomous AI agents become integral to applications, they need to authenticate on behalf of users, access sensitive data, and maintain detailed audit trails. Legacy authentication providers are retrofitting decades-old architectures while Clerk is built with AI-native flexibility.

Clerk’s recently launched Agent Toolkit provides native integration with leading AI frameworks including Vercel’s AI SDK and LangChain, plus MCP support for seamless AI agent interactions while maintaining enterprise-grade security.

But Clerk’s vision extends beyond authentication and into a comprehensive user management platform: the central nervous system for user identity, connecting authentication to billing, permissions, fraud detection, analytics, and customer management. By owning the user identity graph, they can expand into any workflow that touches user data, mirroring successful platform strategies like we saw with Stripe, which started with developer-friendly payments and evolved to becoming the financial infrastructure for the internet.

ALL IN on Clerk 

At Menlo Ventures, we back founders who make powerful technologies effortlessly accessible to developers. Clerk sits at the apex of three core investment areas for us: AI infrastructure, developer tools, and security. They’re building AI-native authentication capabilities while delivering best-in-class developer experiences and enterprise-grade security—combining the themes we see across portfolio companies like Anthropic, Harness, Semgrep, OpenRouter, and Abnormal AI.

We’re excited to partner with the Clerk team as they build identity infrastructure for the AI era. The shift toward component-based, AI-native development is booming, and Clerk is building the authentication platform to enable it.