Full-Stack Engineer Intern

We're looking for engineers who can turn research prototypes into production-ready systems. You'll work at the intersection of browser automation, agent infrastructure, and intuitive UX that make complex agent behavior understandable and controllable.

Preferred: History of high-achieving projects/work experience, open source contributions, or competitive math/cs/physics experience.

What You'll Do

Full-stack browser extension interfaces based on research prototypes.
End-to-end features using React/Next.js, Python, and SQL.
Design intuitive interfaces for how users should delegate and override AI actions.
iMessage, communications channels, desktop-native, wearables integrations

Requirements

Strong foundation in React/Next.js and TypeScript.
Experience building and shipping complex web apps and/or browser extensions.
Familiarity with design systems like Figma
Preferred: Proof of meaningful open-source contribution.
Preferred: Strong UI/UX or design portfolio.

Sample Projects

Reusable tool call and output components for LLM-generated responses.
Building efficient indexing, search, and memory layer architecture.
Developing security and guardrails to approve and deny agent requests.
Integrating third-party platforms (e.g. Slack, Notion, Gmail) to enable workflows.

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.

Summer 2026 Full-Stack Engineer Intern

About the role

Full-Stack Engineer Intern

What You'll Do

Requirements

Sample Projects

About Dex

Other roles at Dex

Job details

Company

Funding

Founders

What happens next.

Confirm the fit

I pitch you to the company

A meeting lands on your calendar