Surviving Two Seed Extensions, Fixing Auth for AI Agents | Clerk Founder & CEO Colin Sidoti

Colin Sidoti is the Co-founder and CEO of Clerk, the best way to build authentication and user management.

I loved this conversation, because Colin is currently in the arena building Clerk. It has not been easy, and he takes us inside some of the harder moments of the past six years.

We hit on three main themes: authentication; lessons raising multiple hard Seed extensions in the early days, including a recap before the A, and the demo that got a16z to invest; and things AI and MCP.

We also talk founding a company with his brother, building a compound startup, why components are the new APIs, and what he learned about audacious goals from John Collison @ Stripe

A big thank you to Reid Christian @ CRV, Paul Klein @ Browserbase, and Joseph Nelson @ Roboflow for helping brainstorm topics for Colin.

Timestamps:

(3:39) The best developer tool for authentication and user management

(5:45) The easiest way to set up billing

(7:13) Building a compound startup

(9:15) Lesson on audacious goals from John Collison

(12:40) Developer tools are now trusted category experts

(13:47) How auth impacts billing, CRM, marketing, analytics

(19:44) Why auth is always changing

(25:40) Coming up with the idea for Clerk

(29:24) What its like starting a company with your brother

(30:58) Living in a basement during Clerks early days

(35:33) Getting early users narrowing focus in South Park Commons

(40:10) Fundraising lessons from struggling to raise

(43:46) The trick that raised Clerk’s first round from S28

(45:09) Launching + the first Seed extension

(50:15) Sequoia’s feedback that improved conversion rates

(52:22) Why a16z led Clerk’s 2nd Seed extension

(58:11) How to do a recap before Series A

(1:03:34) Changing Clerk’s pitch to scare investors

(1:08:56) Fundraising advice “Why partner alignment is all that matters”

(1:11:42) Fast Series A and breaking 7%/week growth

(1:16:32) Negotiating Clerk’s Series B at the bar

(1:22:15) Investors in the arena vs in their mansions

(1:27:57) The three ways AI is changing authentication

(1:31:21) Why AI agents all try to steal free AI credits

(1:33:09) Remember to have fun

(1:36:24) Building a better product to compete in a crowded market

Referenced

Try Clerk: https://clerk.com/

Jobs at Clerk: https://clerk.com/careers

Martin Casado’s tweet https://x.com/martin_casado/status/1558134697753841664

Try Inngest: https://www.inngest.com/

Follow Colin

Twitter: https://x.com/tweetsbycolin

LinkedIn: https://www.linkedin.com/in/colin-sidoti-751a219

Follow Turner

Twitter: https://twitter.com/TurnerNovak

LinkedIn: https://www.linkedin.com/in/turnernovak

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