Achievements
- Joined Y Combinator's S24 batch
- Co-founded Stack Auth, an open-source auth platform challenging Auth0
- Built Umi, a language learning app with over 100K downloads
- Worked as a machine learning engineer at DeepJudge, using AI to detect legal fraud
- Backed by Guillermo Rauch and other major investors
- Customers include Google, Bloomberg, and DeepJudge
The deal with Zai Shi
Mad respect for Zai Shi – the dude’s a straight-up tech whiz and a legit startup grinder. He’s part of Y Combinator’s S24 batch, which is basically the red carpet for the future trend. Zai co-founded Stack Auth, an open-source auth platform that’s basically a middle finger to all the boring, expensive solutions like Auth0. Think of it as the real deal for devs who wanna customize their login and security stuff without the bullshit.
Before jumping into Stack Auth, Zai was deep in the trenches as a machine learning engineer at DeepJudge – yeah, those guys that use AI to spot legal fraud. But he’s not just some AI nerd; he’s also a founder at heart. He co-founded Umi, a language learning app that hit over 100K downloads. That’s no small feat – shows he’s got the hustle and knows how to build stuff people actually want.
Stack Auth? It’s his latest move, and he’s crushing it. The platform’s got killer React components, dashboards, libraries for Next.js, React, JS – all developer-focused. Basically, he’s making life easier for devs, giving them open-source tools that are customizable and strong. And he’s got some serious backers – Guillermo Rauch, the guy behind Next.js and Vercel, is in his corner. Plus, big names like Google, Bloomberg, and DeepJudge are already customers. That’s some real validation right there.
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Talk to herWhat’s crazy is, Zai’s not new to this game. He’s a repeat founder, always jumping into new tech, always building. His background screams someone who’s driven by solving real problems, not just chasing shiny objects. Starting Umi, then working in ML, then launching Stack Auth – it’s all about pushing boundaries and making stuff that matters.
Bottom line? Zai Shi is one of those dudes who’s just wired to innovate. He’s got the technical chops, the hustle, and the vision to shake up the devtools world. Watching him build Stack Auth from scratch, backed by big names, and already making waves? No cap – this guy’s gonna be a major player in the tech game.

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