Frontend Software Engineer

trg.; Greater London; Hybrid; GBP 65,000 - 90,000; Full time

Job summary

trg. in London invites a Frontend Software Engineer to join a climate-tech nonprofit and work on a modern React/TypeScript codebase with ownership over significant frontend features.

You will build data-heavy interfaces, complex grids, visualisations and AI-enabled product features, collaborating with Product, UX, backend engineers and energy specialists in a hybrid setup.

Qualifications

• 3+ years building production frontend applications with React and TypeScript.
• Built complex, data-heavy interfaces involving tables, filtering, forms or visualisations.
• Experience with frontend testing across unit, component, integration or E2E levels.
• Interested in accessible, reusable frontend components and modern architecture.

Responsibilities

• Develop data-rich frontend features with React and TypeScript.
• Build and optimise large data grids and visualisations.
• Collaborate closely with Product, UX, backend and AI engineers.
• Deliver high-quality, accessible UI components with strong performance on large datasets.

Skills

React

TypeScript

Data-heavy UI

Performance

TanStack Query

Testing

Accessibility

Collaboration with Product/UX

Tools

AG Grid

D3

AG Charts

TanStack Table/Virtual

Parquet

Job description

Frontend Software Engineer — Climate Tech Nonprofit

London Hybrid — 2 days in London / 3 remote

I’m working with a climate-tech nonprofit building software that helps governments, policymakers and energy planners make better decisions about the transition to cleaner electricity systems.

This isn’t a standard frontend CRUD role.

The frontend engineering problems are genuinely interesting.

You’ll be building spreadsheet-like interfaces, interactive visualisations, filtering workflows and complex data-heavy features over datasets that can run into millions of rows — including input tables of around 5.1 million rows, well beyond what Excel can handle.

They’re now looking for a Frontend Software Engineer to join a small interface team working on a modern, greenfield React and TypeScript codebase.

You’ll work closely with a Principal Frontend Engineer, Product, UX, backend engineers, AI engineers and energy specialists, with plenty of ownership over the features you build. The work can vary significantly sprint to sprint — from large data grids and visualisation to AI-powered product features.

• Have 3+ years building production frontend applications with React and TypeScript
• Have built complex, data-heavy interfaces involving tables, filtering, forms or visualisations
• Understand frontend performance and how to work efficiently with large datasets
• Have experience with client-side caching, synchronisation and invalidation — TanStack Query or similar
• Have worked with frontend testing across unit, component, integration or E2E levels
• Enjoy building reusable, accessible components and modern frontend architecture
• Are comfortable working closely with Product, UX and backend teams
• Enjoy solving difficult frontend problems rather than simply implementing standard screens

Experience with AG Grid, D3, AG Charts, TanStack Table/Virtual or Parquet would be particularly useful, but isn’t essential.

Climate or energy experience isn’t required either — they’re much more interested in strong frontend fundamentals and people who enjoy technically challenging product engineering.

This is a good opportunity for someone who wants meaningful ownership, technically difficult frontend work and the chance to build software that has an impact beyond commercial optimisation.