Job Description

Software Engineer (Intern)

San Francisco, CA, USA • Internship

ThirdLayer is solving one of the hardest problems in deploying agents: AI models are generic, but people's work and processes are specific. Our product, Dex, embeds within your computer and team, ingesting a continuous stream of data across your browser and work apps to understand how you actually operate. So when you delegate tasks, agents know exactly the context of where information lives and how decisions get made. We're a deeply technical team with a high bar for talent and a shared belief that exceptional people are the foundation of everything we build.

The Role

We're looking for product engineer interns who care deeply about the craft of building software: clean architecture, thoughtful API design, strong typing, and interfaces that are a pleasure to use. How people interact with agents is a fundamentally unsolved problem. Users expect first-minute magic, polished experiences, and a product that gets better the more they use it. You'll ship features across our browser extension, web surfaces, and platform, working closely with other engineers and our users to push the boundaries of how people work with agents. You'll go from whiteboard to production and own the outcome.

What You'll Do

• Ship product and talk to users. Build performant, beautiful experiences that people genuinely enjoy using.
• Own features end-to-end: gather context, scope the work, build it, ship it, and make sure it holds up.
• Define how users interact with agents across our surfaces.
• Build shared libraries, component systems, and internal tooling that make the rest of the team more productive.
• Work closely with the team on product direction, understand how customers use what you build, and let that shape what you build next.
• Build integrations and data pipelines that connect our platform to external systems.

What We're Looking For

• A strong engineer with attention to detail, thoughtful about UX, and deeply empathetic toward users.
• Strong fundamentals in TypeScript and/or Python. You write well-typed, well-structured code and take pride in it.
• You've built and shipped real software, whether personal projects, open source, or at a company.
• You're at your best when you own a problem end-to-end, comfortable with ambiguity and energized by turning vague asks into clean solutions.
• Good visual and interaction judgment, even if you're not a designer by title.
• Willingness to move fast and grow quickly in a rapidly changing environment.
• Strong communicator who can work closely with teammates and customers.

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