Developers building front-end Jamstack web applications often struggle to build identity with traditional API tools. With the approach growing in popularity, the founders of Clerk decided to focus their startup on building a simplified identity tool purpose-built for React applications.
The company announced a $15 million Series A led by Madrona today.
Colin Sidoti, who started the company with his brother Braden, sees what’s happening with Jamstack and React as a fundamental architectural shift where front-end developers will increasingly have a seat at the table.
When they started the company, they began with the idea of building a straight identity API, but there wasn’t a huge amount of differentiation from what they saw already in the market with Auth0. That’s when they decided to focus on identity for the growing Jamstack crowd instead.
What the Sidoti brothers did was to build a solution of React components, rather than going the API route the way Auth0 did. It allows developers to drop identity into their application in a few minutes, rather than taking hours trying to build it.
“I think React, and really the architecture shift that comes along with it, is going to win. We see [companies like] Vercel really changing the way developers think about hosting. You can say they’re focusing on React, or you can say they’re focusing on Next.js, but I look at as they’re focusing on is this front end developer, the person responsible for the interface is suddenly more of a stakeholder than they’ve ever been before,” Sidoti told TechCrunch.
The solution seems to be resonating with the developer community, growing 500% in just five months with a million users under management. The startup offers a free plan, then three tiered pay plans called Hobby, Business and Enterprise, with different features depending on the plan.
Techcrunch eventJoin 10k+ tech and VC leaders for growth and connections at Disrupt 2025
Netflix, Box, a16z, ElevenLabs, Wayve, Sequoia Capital, Elad Gil — just some of the 250+ heavy hitters leading 200+ sessions designed to deliver the insights that fuel startup growth and sharpen your edge. Don’t miss the 20th anniversary of TechCrunch, and a chance to learn from the top voices in tech. Grab your ticket before Sept 26 to save up to $668.
Join 10k+ tech and VC leaders for growth and connections at Disrupt 2025
Netflix, Box, a16z, ElevenLabs, Wayve, Sequoia Capital, Elad Gil — just some of the 250+ heavy hitters leading 200+ sessions designed to deliver the insights that fuel startup growth and sharpen your edge. Don’t miss the 20th anniversary of TechCrunch, and a chance to learn from the top voices in tech. Grab your ticket before Sept 26 to save up to $668.
San Francisco | October 27-29, 2025 REGISTER NOWClerk currently has 26 employees and they’re hiring, looking to add around 15 people this year. “We absolutely are hiring. The system needs to scale and we need engineers to scale it. Sales pipelines are finally growing, so we’re hiring on the sales side as well. And then there’s always just like product surface area growth,” he said.
He says that they are working to be more diverse, recognizing that they lacked diversity in their early hiring. “We actually hired a lot in Greece early on. And so for the longest time, our company was just a bunch of Greek men. And that wasn’t particularly helpful to diversity and I think we saw the traditional struggles that come with the lack of diversity. And so it’s become a focus point in hiring. A lot of that is just like working with recruiters that are better at getting into other networks,” he said.
Madrona’s managing director, Karan Mehandru, will be joining the board under the terms of the deal. He was an early investor in Auth0 and sees a lot of similarities in Clerk in a more modern context.
“Clerk is a foundational technology company dedicated entirely to serving the needs of the next generation of application developers as the authentication industry migrates from back-end APIs to front-end componentized modules,” he said in a statement.
It’s interesting to note that Vercel’s CEO Guillermo Rauch is also an investor in today’s round, along with Mango Capital, Andreessen Horowitz, S28 Capital and Fathom Capital.