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Founding Engineer

ThirdLayer· Engineering
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Hybrid (San Francisco, CA)$130k - $250kFull-timePosted 11mo ago

About the role

Founding engineer role at Thirdlayer (Dex) building an in-browser AI action layer with memory, context, and agentic workflows. Focus on high-performance infrastructure, browser-native AI, and real-time systems.

Responsibilities

  • Core agent components, including memory stores, context compression, inter-agent protocols, planning and tool use.
  • High performance state management and real-time UI observation systems.
  • Scalable infrastructure for browser-native AI.

Qualifications

  • Expert in React/Next.js, TypeScript, and Python.
  • Deep browser internals experience.
  • Proven rapid prototype to production track record.
  • Preferred: Prior experience with AI/ML infra or agentic systems.

Skills

Required:ReactTypeScriptPython
Nice to have:Natural Language Processing
Last updated Sep 16, 2026. Interested? Apply on the company site.
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About ThirdLayer

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.

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