Clerk Announces $6.2M Seed Funding To Build Authentication And User Management Tools For React

SAN FRANCISCO--()--Clerk, the drop-in authentication and user management solution for React, announced today that it has closed a $6.2m seed round led by Andreessen Horowitz. Existing investors S28 Capital, Fathom Capital, and South Park Commons also joined the round. This new funding will allow Clerk to expand its suite of authentication and user management tools, and create new tools to help B2B SaaS companies manage both user accounts and business accounts.

Clerk empowers React developers to build sign-up and sign-in flows as well as user profiles without the assistance of backend developers. The solution comes complete with security essentials like multi-factor authentication and active device management. The beautifully designed React components can be customized to match any company's branding. By providing a full stack solution, Clerk minimizes the time engineers need to spend on authentication, freeing up development resources to focus on the core of their business.

The vast majority of authentication solutions on the market today are still managed in-house and are often incomplete and fail to meet security best practices. Many of these solutions are dated, as web development technologies have evolved to component-based frontend technologies like React. With Clerk’s solution, developers are getting what they prefer—components—because they help them move faster. Components are especially appealing in authentication and user management where businesses do not get much benefit from reinventing the wheel of self-serve 2FA or avatar-uploading. Clerk includes both in their <UserProfile/> component.

"Our key insight is that React Components have replaced REST APIs as the premier developer experience," said Colin Sidoti, Clerk cofounder and CEO. "Since components have a built-in backend and presentation layer, they're an order-of-magnitude faster to implement than APIs."

While Clerk is intended for React frontends, the authentication solution works with any framework, programming language, or API gateway on the backend. This approach has been especially helpful for legacy web applications that are transitioning to React on the frontend, but do not want to change their backend technology.

"There's a growing preference for React among businesses of all sizes, and devtools must evolve to cater to this new architecture. Clerk is hands-down the easiest and most-complete approach to auth and user management in React today," said Martin Casado, General Partner at a16z. "We are excited to help accelerate Clerk's growth and reach more businesses, founders and startups who are looking for easy authentication and user management."

Clerk's vision is to build a truly complete customer management solution for developers, helping facilitate authentication, authorization, communications, billing, and more. Clerk believes these essential services can all be bundled together, and presented cohesively in simple React components.

Notable startups using Clerk include database company Grafbase, women's shapewear company Honeylove, and apartment rental company Blueground. Clerk's React-optimized solution has led the company to be included in Netlify's Jamstack Innovation Fund, and named one of the 10 most promising Jamstack startups.

About Clerk

Founded by brothers Colin Sidoti and Braden Sidoti in 2019, Clerk offers drop-in authentication and user management for React developers. Clerk is backed by Andreessen Horowitz, S28 Capital, Fathom Capital, South Park Commons, and Netlify. Learn more at


Colin Sidoti,

Release Summary announces $6.2 million seed funding from Andreessen Horowitz for their user authentication and management solution for React.


Colin Sidoti,