Clerk, the authentication startup, lands $30M and inks a strategic deal with Stripe

Clerk, a startup creating a suite of embeddable UIs, APIs and admin dashboards that app developers can use to authenticate and manage users, has raised $30 million in a Series B round led by CRV with participation from Stripe, Andreessen Horowitz and Madrona.

The proceeds bring Clerk’s total raised to $55.5 million, and co-founder and CEO Colin Sidoti says that they’ll be put toward expanding Clerk’s service beyond authentication and into authorization — i.e. determining the permissions a user has versus simply identifying who they are.

“Authorization has always been part of our product vision, but we needed a successful authentication product to build atop,” Sidoti told TechCrunch in an email interview. “Clerk’s authentication service had phenomenal growth in 2023, and now there’s a backlog of customers asking for authorization.”

Clerk was founded in March 2019 by Sidoti and his brother, Braden. Both are engineers — Colin has a degree from MIT, while Braden graduated from Washington University in St. Louis and previously worked at Uber and Inspirato.

Clerk builds developer tools for authentication, offering drop-in components coded in React, the open source frontend JavaScript library. Clerk attempts to detect malicious activity, like bots, while managing user data on behalf of customers.

“Despite authentication and authorization being ubiquitous challenges across every software company, they have been exceptionally slow to become outsourced,” Colin said. “When you ask developers why, they often highlight that authentication and authorization are too tightly-coupled to the rest of their application to outsource. To work around this, Clerk defines authentication a little differently than our competitors: in some areas we do more, in others we do less.”

Clerk — primarily a self-serve platform, with pricing based on the number of monthly active users — will soon integrate Stripe Billing to determine user permissions based on their subscription plan. The integration is motivated in part by the investment from Stripe, which Colin says marks the beginning of a “strategic partnership” between the two firms.

“Stripe Billing helps developers create and manage user subscriptions,” he added “Since permission to access certain features typically depends on the user’s subscription plan, Clerk requires a tight integration with Stripe Billing to create a robust authorization solution.”

Clerk, which claims to have around 1,300 paying customers and 16 million users under management for those customers, plans to grow its workforce from 55 people to 80 by the end of the year as it competes against upstarts like Descope, Stytch and WorkOS. “2023 was a phenomenal year for Clerk, and we anticipate continued acceleration in 2024,” Colin said.