ThirdLayer
ThirdLayer is a YC Winter 2025 (W25) company. Based in San Francisco, CA, USA. Team of 2.
About ThirdLayer
Summary
ThirdLayer builds Dex, a browser-native AI copilot for knowledge workers and operators handling complex, multi-tool workflows. Dex maintains a live operational graph across messages, meetings, deals, and tasks, then uses that accumulated context to drive autonomous agents, fill forms, and execute work directly in the browser. It replaces the manual effort of context-switching, status tracking, and repetitive handoffs across tools like Gmail, Slack, and CRMs.
Business model
A paid plan, with pricing listed on the website.
Go-to-market
Dex targets operators and knowledge workers who install the Chrome extension and book an onboarding call, combining self-serve installation with a guided setup to activate the product.
From the Y Combinator listing
Building Dex, the AI Browser Copilot
ThirdLayer is an applied research and product lab building the next interface for human–AI collaboration. Our first product is Dex, an AI copilot for the browser. Think Cursor for knowledge work, optimized for speed and embedded directly where you work. Most web agents are built for set-and-forget tasks. But real work is fluid and messy—spread across tabs, tools, and evolving decisions. Dex transforms your browser into an intelligent, multimodal workspace that understands your intent through voice, text, and action. It enhances familiar interfaces, automates tedious steps, and removes the friction of handoffs. Beneath the surface, Dex is more than a browser agent — it’s a foundation for: ● Long-term, cross-modal memory grounded in real workflows ● A new interaction layer to replace static UI with a collaborative canvas ● Personalization: understanding how individuals approach tasks and navigate software We're building the infrastructure for adaptive, intent-aware systems that work the way you do.
Facts
- B2B / B2B
- San Francisco, CA, USA
- 2
- Active
- Early
Founders (2)
- Kevin Gu
- Regina Lin
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