Senior Frontend Engineer, Design System

synthesia; United States; Hybrid; USD 160,857 - 241,286; Full time

Benefits offered by this job

25 days leave + local holidays

Job summary

Synthesia is a leading AI video platform. We are seeking a frontend engineer to own and evolve the design system, building a scalable component library, tokens and documentation for product teams.

You will extend the system for AI-assisted development, focusing on robust APIs, accessibility, and a smooth developer experience. You’ll work with design, product and engineering to productionize components, ensure WCAG-compliance, and implement theming and localisation for a global audience.

Qualifications

• Five years as software engineer with three at senior level, owning a design system or shared component library.
• Deep frontend: HTML, CSS, JS/TS, strong React, modern tooling.
• Strong API design and developer experience for shared libraries.
• Experience or interest in AI-ready component libraries.
• Responsive design, cross-browser compatibility, performance.
• WCAG 2.2 AA / EN 301 549 accessibility as part of done.
• Craft, attention to detail, balance design and engineering constraints.
• Strong communication and collaboration, improving developer productivity.

Responsibilities

• Build, scale and evolve the design system, component library, design tokens and docs for consistency.
• Extend the design system for AI-assisted development with Storybook and MCP interfaces.
• Design component APIs to resist misuse for both human and AI developers.
• Write high-quality frontend code (React/TypeScript) and ensure component craft.
• Collaborate with design, product and engineering to take components to production.
• Ensure components are accessible by default and collaborate with Accessibility engineer.
• Own developer experience: docs, guidelines, Storybook, versioning and migration paths.
• Implement theming, multi-brand support, and localisation/RTL for global audience.
• Continuously improve system based on adoption metrics and feedback.
• Shape design system direction and champion adoption across teams.

Skills

Frontend expertise

React

HTML/CSS/JS/TS

Design system ownership

API design

AI-ready libraries

Accessibility (WCAG)

Communication/collaboration

Tools

Storybook

MCP interfaces

Job description

Synthesia is the world’s leading AI video platform for business, used by over 90% of the Fortune 100. Founded in 2017, the company is headquartered in London, with offices and teams across Europe and the US.

As AI continues to shape the way we live and work, Synthesia develops products to enhance visual communication and enterprise skill development, helping people work better and stay at the center of successful organizations.

Following our recent Series E funding round, where we raised $200 million, our valuation stands at $4 billion. Our total funding exceeds $530 million from premier investors including Accel, NVentures (Nvidia's VC arm), Kleiner Perkins, GV, and Evantic Capital, alongside the founders and operators of Stripe, Datadog, Miro, and Webflow.

About the role

• Build, scale and evolve our design system: the component library, design tokens, and documentation that give product teams a consistent, accessible foundation to build on.
• Extend our design system for AI-assisted development so AI coding tools and agents can use our components, tokens and guidelines as easily as people can, with Storybook as the backbone and machine‑readable interfaces (e.g. MCP) layered on top.
• Design component APIs that resist misuse, so AI and human developers alike can build with confidence.
• Write high‑quality, performant frontend code (React/TypeScript) and raise the bar for component craft and consistency across the engineering org.
• Partner closely with design, product and engineering to define components together and take them all the way to something that holds up in production.
• Make our components accessible by default, meeting WCAG 2.2 AA, and work closely with our Accessibility engineer to bake in best practices from the start.
• Own the developer experience of the design system: clear documentation, guidelines, Storybook, sensible component APIs, versioning and smooth migration paths that make adoption easy for both human and AI consumers.
• Implement and maintain theming, white labelling, and localisation/RTL support so the system works for a global audience.
• Continuously improve the system based on adoption metrics, contributor feedback and new platform capabilities.
• Shape the technical direction of the design system over the next 6–12 months, championing its adoption across teams.

What we're looking for

• At least five (5) years as a software engineer, including three (3) at senior level, building frontend platforms, with real ownership of a design system or shared component library used across multiple products.
• Deep frontend expertise: expert HTML, CSS and JavaScript/TypeScript, with strong React and familiarity with modern build tooling.
• A strong command of component API design, versioning and the developer experience of shared libraries.
• Experience (or strong interest) in making component libraries consumable by AI.
• Solid understanding of responsive design, cross‑browser compatibility and web performance.
• Comfortable building components to WCAG 2.2 AA / EN 301 549 and verifying them yourself with a keyboard and screen reader — accessibility is part of your definition of done, not a separate pass.
• A strong sense of craft and attention to detail, and the ability to balance design intent with engineering constraints.
• Strong communication and collaboration skills, and a passion for improving developer productivity and end‑user experience.

Nice to haves

• A strong design sensibility — an eye for visual detail and the judgement to push back on and improve design decisions, not just build them.
• Experience implementing multi‑brand theming in production.
• Experience with localisation and internationalisation (including RTL) for a global audience.

Other important info

• Our preference is for this role to be based either in‑office or remote in London, UK. We can also accommodate remote workers in other locations across Europe subject to compliance and right to work checks.
• The salary starts at EUR/GBP/CHF 120,000 base + stock option plan.
• This is full‑time employment only, usually through OysterHR. No contractors possible.
• Everyone at Synthesia gets 25 days of leave + local holidays (no extra paid or unpaid leave possible).
• We only sponsor VISA if you are in the UK/EU country already and need support.