Summer 2026 Full-Stack Engineer Intern
San Francisco, CA at a glance
- Rent
- #2 of 51$2,680/mo+46% vs US avg
- Weather
- #17 of 51295 mild days0 hot · 0 cold
- Income tax
- #1 of 5113.3% top rateCalifornia
What you need
- Strong foundation in React/Next.js and TypeScript.
- Experience building and shipping complex web apps and browser extensions.
- Familiarity with design systems like Figma.
- Proof of meaningful open-source contribution.
- Strong UI/UX or design portfolio.
What you'll do
- Build full-stack browser extension interfaces from research prototypes.
- Develop end-to-end features using React/Next.js, Python, and SQL.
- Design intuitive interfaces for delegating and overriding AI actions.
- Integrate iMessage, communications channels, desktop-native, and wearables platforms.
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.
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About Thirdlayer
ThirdLayer is the learning and alignment layer for enterprise AI. We continuously ingest and structure messy organizational context, complex operational processes, and siloed, permission-sensitive data, then grade agents against the outcomes each company cares about. Every interaction becomes feedback that helps agents improve over time. Companies use ThirdLayer to power their internal agents or embed it into the AI products they’re building. We give agents the context, evaluations, and learning loops they need to stay aligned with each organization and deliver better outcomes with every run.
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