Senior Frontend Developer

You sweat the details. You open a SaaS app and immediately notice the component that shouldn't be a modal, the auth flow nobody thought through, the table that takes half a second too long to load. Most engineers file a ticket. You fix it — and then you make sure it never happens again.

That instinct is exactly what this team needs.

The company

This is an AI‑native integration layer for SaaS products and agents: unified APIs, MCP‑friendly tooling and A2A (agent‑to‑app and app‑to‑app) bridges so builders can wire their products into hundreds of third‑party tools without hand‑rolling every integration. It handles managed auth, real‑time observability and connector sprawl so product teams can focus on great agent experiences instead of glue code. Your job is to make the surface they see feel as well‑engineered as the plumbing underneath.

Why this role exists

The product experience is the brand. This is the first dedicated UX Engineer role — you’ll be the in‑house authority on taste, polish and performance. You won’t be one of many contributors to the front end; you’ll set the standard everyone else works to: the component library, the design system, the micro‑frontend architecture, and the AI rules and tooling that let the rest of the team move fast without making a mess.

As the CTO put it in conversation: “It’s about setting the processes, the libraries, the tech stack… spreading the knowledge so that everyone can go to 90% of your level.”

What you’ll actually do

• Own the design system – define the visual language, build reusable primitives, and maintain the libraries that power every interface.
• Ship pixel‑perfect UI in React, with real ownership of theming, performance and motion.
• Make performance a feature – instrument Core Web Vitals, set bundle budgets, optimise hydration patterns and chase performance where it actually matters.
• Be the voice of quality – host design critiques, push back on product design when it matters, and be the person who asks “what happens in this edge case?”.
• Prototype and validate – turn product ideas into interactive proofs‑of‑concept that help PMs and designers converge on the right answer fast.
• Lift the whole team – create AI‑powered tooling and internal rules so every engineer can contribute to the front end at your level.

The split is roughly 70–80% front end, 20–30% back end (Node, React‑router, SvelteKit) — enough to remove performance bottlenecks without being a full‑stack role.

Who you’ll work with

You’ll report directly to the technical leadership and work most closely with the Product Manager and Product Designer day‑to‑day. The team is fast, flat and product‑focused: engineers own their features end‑to‑end and interact with product directly, so your decisions will show up quickly in what customers use.

Must‑haves

• 4+ years professional front‑end engineering, with a portfolio that shows you care about the details.
• React & TypeScript at production scale (hooks, suspense, server components).
• Deep CSS fluency (Tailwind or equivalent) and modern browser APIs.
• A strong UX sense for B2B SaaS flows — you’ve lived through auth flows, billing pages and dashboards, and you know where the traps are.

Nice to have

• Svelte, Web Components or other framework experimentation.
• Experience with auth flows (OAuth2, OpenID Connect) and secure front‑end patterns.
• Prior work on B2B developer tools or dashboards at the seed‑to‑Series‑B stage.

What’s on offer

• £80,000–£100,000 base  + annual company performance bonus.
• Meaningful EMI share options.
• £15/day lunch budget when working from the London office
• £1,000 home office setup + £500/year top‑up.

If you read this far and you'd like your CV reviewed by a human, email mark@seekr.inc with "Watch me React" in the subject line. A couple of lines on why you think this might be a good fit — that's all.