Senior Frontend Software Engineer - AI Copilot

Zendesk

Lisbon or Remote, Portugal

We are looking for a Senior Frontend Engineer to join our AI Copilot organisation. AI Copilot is a multi-million ARR product that puts AI directly into the hands of customer service agents and administrators. You will own the user-facing experience of AI-powered features — building the interfaces where admins and agents interact with Copilot — taking significant pieces of work from design through to production.

What you'll be doing

Own and deliver end-to-end product features — from technical design through implementation, testing, release, and iteration — with a focus on the frontend experience.
Build accessible, performant, and maintainable UIs in React and TypeScript, using our Garden design system.
Partner with Product Design to turn designs and prototypes into polished, production-ready interfaces, and push back constructively on tradeoffs.
Work closely with backend, ML Scientists, and ML Engineers to integrate AI-powered capabilities into reliable, user-facing features — including streaming responses, latency handling, and graceful failure states.
Contribute to frontend architecture decisions within your team (component design, state management, performance), with growing influence across teams.
Improve the reliability, performance, and maintainability of the systems you work on — proactively identifying and addressing technical debt.
Occasionally reach into the backend (APIs, integrations) to unblock yourself and ship features end-to-end.
Mentor more junior engineers through code review, pairing, and knowledge sharing.

What you bring to the role

Required

5+ years of experience building and operating large-scale, Internet-facing web applications.
Strong proficiency in modern frontend development: JavaScript/TypeScript, React, and the browser platform (state management, performance, accessibility).
Solid understanding of building against RESTful APIs and integrating with backend services; comfortable reading and making small backend changes when needed.
Experience with CI/CD practices and shipping to production frequently.
A track record of owning features end-to-end and delivering them to production with high quality.
An eye for UX and design detail — you care about how the product feels, not just whether it works.
Ability to work with uncertainty and the flexibility to pivot with changing priorities.
Comfort working in a team alongside backend, ML engineers, and scientists — you don't need to be an ML expert, but you should be curious and able to collaborate effectively across disciplines.
Strong collaboration skills and a genuine desire to help the team succeed.

Preferred

Experience building UIs on top of LLM-powered features — streaming/token rendering, chat interfaces, evaluation, or handling non-deterministic responses gracefully.
Familiarity with design systems and component libraries at scale (Garden, or equivalents).
Working proficiency in Ruby or Python — enough to navigate our backend services and make small changes.
Exposure to containerised deployments (Docker, Kubernetes) and cloud infrastructure (AWS).
Experience with iterative, metrics-driven product development (A/B testing, feature flags, incremental rollouts).
Familiarity with frontend observability and performance monitoring (Core Web Vitals, error tracking).