0->1 Engineer

USA💼 Full-time💰 $200,000–$200,000🗓 2026-09-27 → 2026-09-29

Core

Building open-source AI tooling and browser extensions (Harbor) to implement Web Agent API standards, ensuring user control over model permissions and agent oversight.

Role type

Senior IC browser engineer (open source AI)

Builds

Browser extensions, SDKs, MCP servers, and reference implementations for Web Agents API

Domain

Open source AI, browser engineering, web standards

Required skills

Python, TypeScript, WebExtensions API, MCP server authoring, local model inference (Ollama, llama.cpp), prompt injection mitigation, layered architecture design

Preferred skills

WASM MCP tooling, OAuth integration, capability system design, WICG/W3C standards familiarity

Technologies

Firefox, Chrome, WebExtensions, Ollama, llama.cpp, WASM, MCP

Responsibilities

Ship working tools and demos for Harbor and open source AI tooling; fix architectural gaps in function calling, streaming, and permission granularity; engage with WICG/W3C standards processes; maintain clean, readable codebase and documentation for community use

Seniority

Senior, hands-on IC

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About Mozilla

Mozilla exists to build the Internet as a public resource accessible to all because we believe that open and free is better than closed and controlled. When you work at Mozilla, you give yourself a chance to make a difference in the lives of Web users everywhere. And you give us a chance to make a difference in your life every single day. Join us to work on the Web as the platform and help create more opportunity and innovation for everyone online.