Senior front end developer (react.js/next.js) Work, Jobs (with Salaries)

Senior UI Engineer
StackOne —London
- Full-time
- Hybrid work
- APIs
Senior Specialist - Software Engineering
LTM —London
- JavaScript
- Software development
- APIs
Quick apply
Senior Software Engineer
Shield Safety Group —Manchester
- Up to £55,000 a year
- Hybrid work
- Azure
- Administrative experience
- SQL
- Employee assistance programme
Software Developer - Clearing Technology
Marex —London
- Full-time
- AWS
- JavaScript
- Software development
Quick apply
Contract Java/Angular Developer
AND Digital —London
- Hybrid work
- DevOps
- Java
- Agile
Quick apply
1d
Web & Cloud Infrastructure Developer
Coder Agency —Norwich
- Full-time
- Hybrid work
- Computer Science
- AWS
- JavaScript
Quick apply
Manager, UX Development
Elekta —Crawley
- Management
- Computer Science
- Engineering
- Annual leave
- Work from home

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Senior UI Engineer
StackOne —London
Prototype & validate – turn product ideas into interactive proofs-of-concept that help PMs and designers converge on the right solution fast.
Senior Software Engineer
Shield Safety Group —Manchester
RiskProof is widely used across industries including hospitality, retail, and leisure, where operational consistency and compliance are critical.
Up to £55,000 a year

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Senior UI Engineer

StackOne
London

Apply Now

Job details

Full-time

Benefits

Cycle to work scheme
Private medical insurance

Qualifications

Node.js
CSS
React
APIs
TypeScript
Workday

Full job description

About StackOne:

StackOne is the AI Integration Gateway for SaaS products and AI Agents. Backed by GV and Workday Ventures ($24M raised), we help builders of SaaS platforms and AI Agents orchestrate hundreds of scalable, accurate, and enterprise-grade integrations. Our platform combines 25,000 pre-mapped actions on 200 connectors, an AI-powered integration development toolkit, plus security by design: a real-time architecture, managed authentication and permissions, and end-to-end observability.

Join us on our fast trajectory to build the future of agentic integrations.

Why this role exists

StackOne’s product experience is our brand. As our first dedicated UX Engineer you will be the in-house authority on taste, polish, and performance. You will own the component library, shape our micro-frontend architecture, and ensure that every pixel, motion, and millisecond of latency makes customers feel like they’re using the best-engineered platform on the market.

What you’ll do

80 % Front-end craft & design systems
20 % API-aware performance engineering
Collaborate with our Designer to define & steward our design system – set the visual language, build reusable primitives, and maintain libraries that power every StackOne user interfaces.
Ship pixel-perfect UIs – React (primarily) plus; own theming, performance, and thoughtful motion.
Make performance a feature – instrument Core Web Vitals, budget bundle sizes, optimise hydration patterns, and chase performance where it matters.
Provide and maintain internal tooling as well as AI rules to allow every technical team to contribute to the front-end while aligning with the best practices you will help set.
Prototype & validate – turn product ideas into interactive proofs-of-concept that help PMs and designers converge on the right solution fast.
Champion taste & detail – host design-quality critiques, stamp out visual debt, and be the go-to voice when “good enough” isn’t.

What you’ll bring

Must-haves

4+ yrs professional front-end engineering with a portfolio that focus on the details.
React & TypeScript at production scale; comfortable with hooks, suspense, and server components.
Deep CSS fluency (Tailwind or equivalent) and experience of modern browser APIs.
Proven track record building or migrating component libraries/design systems.
Strong performance tuning instincts: Lighthouse, Core Web Vitals, bundle analysis, code-splitting.
Familiarity with monorepo tooling (NX or Turborepo) and micro-frontend patterns.
Ability to dive into back-end code (Node, React-router, sveltekit) to remove perf bottlenecks, instrument metrics, or adjust API shape.

Nice-to-haves

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

Why Join Us?

Meaningful share options (EMI) - share in the company's success as we grow
25 days holiday + 1 additional day per year of tenure
Private health insurance - including dental & optical
£15/day lunch budget when working from our London office, up to £120/month
£1,000 for your home office set up + £500/year top-up
Annual team offsite to sunny spots (last ones were in Spain and Portugal )
Join one of Europe’s fastest-growing startups
Work with a veteran team of ex-employees of Google, Microsoft, Oracle, Coinbase, JP Morgan and more
Health, fitness and gift card discounts
Cycle2Work and Electric Cars scheme
Hybrid work set up - typically 2 days in the office

Ready to help us change the game for SaaS integrations? Get in touch and let's chat!

We believe diversity drives innovation. We encourage individuals from all backgrounds to apply. As an equal-opportunity employer, we celebrate diversity and are committed to creating an inclusive environment for all employees.

Apply Now

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senior front end developer (react.js/next.js) jobs

Senior UI Engineer

Senior Specialist - Software Engineering

Senior Software Engineer

Software Developer - Clearing Technology

Contract Java/Angular Developer

Web & Cloud Infrastructure Developer

Manager, UX Development

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