Mozilla

0->1 Engineer, Open Source AI

Remote US · Contract

Sponsorship not specified$200k-$227kDetected 82 days ago

JavaScriptTypeScriptPythonGitOAuthResearchCommunication

About the role

The current focus is Harbor, a Firefox and Chrome extension implementing a proposed Web Agent API that puts model choice, tool permissions, and agent oversight back in the hands of the user and the browser, rather than the vendor.
Making those layer boundaries legible is core to the role - if a developer or their coding assistant keeps reaching for the wrong primitive, that's yours to fix.

Ship working tools, demos, and reference implementations on top of Harbor and open source AI tooling - fast. Days, not weeks. Code that makes architectural choices concrete enough for another developer to install, read, fork, and build on.
Real problems on the table right now: proper function calling in the bridge (currently using response parsing), permission granularity beyond origin-level, streaming abort, WASM MCP server tooling, Safari support.
Code that makes architectural choices concrete enough for another developer to install, read, fork, and build on.
We need an engineer who ships fast and in public - working code and real demos that developers can install, fork, and build on.

You know the difference between prototype-quality and production-quality and make that call deliberately.
Hands-on experience with the open source AI stack - inference, orchestration, agent frameworks, evaluation.
You've built something real on top of open models, and you have opinions about where current frameworks get the abstraction wrong.
You have a view on typed-verb surfaces vs.
You can explain layered architectures to developers who don't share your context - in code, in docs, and in writing - clearly enough that developers and their AI assistants route to the right layer without guessing.
You can explain what you built, why you shaped it the way you did, and what's still unresolved.

The thesis is that agents should only be able to do what a page explicitly declares, not free-roam the DOM.

What we're looking for
Mozilla is building a position in open source AI through research, community, tooling, and public advocacy.
A big part of that work is showing, not just telling.

This listing is sourced directly from Mozilla's careers page and normalized into a canonical job model.