Software Engineer (Ruby on Rails)

About Resi Labs

Resi Labs is the technology and innovation arm of Resi, the UK’s largest residential architecture practice. We’re building products that help millions of homeowners make better renovation decisions - from understanding planning feasibility and build costs to visualising what’s possible with their property.

We sit on a unique dataset built over a decade: 2 million planning applications, 40,000 builder quotes, and thousands of detailed floor plans and 3D models linking design, planning, and cost data in ways no one else can. Our products are already embedded on platforms like Rightmove and Zoopla, reaching millions of homeowners per year.

About The Role

We’re looking for a strong Software Engineer (full-stack) to join our product engineering team. You’ll be someone who thinks of yourself as an engineer first, with deep hands-on experience in Ruby on Rails and a genuine passion for building great frontend experiences. You’ll take pride in the quality of what users see and interact with, while being equally capable of working across the full stack to deliver features end-to-end.

As a small, autonomous team, there’s a real opportunity to lead here. To shape technical direction, own meaningful pieces of the product, and have your voice heard.

At the core of what we build is a large dataset and data processing pipeline covering UK property data. You’ll work closely with this data, helping to consume, refine, and unlock its value based on evolving product requirements - so an interest in working with complex, real-world datasets will serve you well.

We’re also fortunate to be working on a relatively greenfield codebase with limited technical debt, meaning you’ll spend your time building thoughtfully rather than fighting legacy decisions. And we’re genuine believers in AI-powered workflows, from how we write code to how the business operates day-to-day, so comfort with and curiosity about AI tooling is a must.

What You’ll Do as our new Software Engineer

• Build polished, responsive frontend experiences using Hotwire (Turbo & Stimulus) and Tailwind CSS
• Design and build full-stack features across our Rails application, from database to UI
• Collaborate with product and design to translate requirements into intuitive, well-crafted interfaces
• Build and consume APIs that power both internal tooling and customer-facing features
• Write clean, well-tested, and maintainable code with a focus on long-term scalability
• Work with our UK property dataset and data pipeline to surface meaningful information through the product
• Participate actively in code reviews, giving and receiving feedback constructively
• Contribute to architectural discussions and help raise the overall quality bar of the codebase

What We’re Looking For

• ~5 years of professional software engineering experience (we care more about the quality of that experience than the exact number!)
• Strong proficiency in Ruby on Rails - you’ve built and maintained production Rails apps and feel genuinely at home in the framework
• A strong eye for frontend quality - you care about how things look and feel, not just whether they work
• Comfortable working with HTML, CSS, and JavaScript across a modern Rails frontend stack
• Familiarity with relational databases (PostgreSQL preferred) and writing efficient queries
• Comfortable building and consuming APIs as part of delivering full-stack features
• Experience writing automated tests (RSpec, Minitest, or similar)
• Good communication skills and a collaborative mindset - you can explain technical decisions clearly to both engineers and non-engineers
• Ability to work independently and manage your own delivery without heavy oversight

Nice to Haves

• Experience with Three.js - we’re actively building 3D visualisation features and this will be an ongoing and growing part of the product
• Experience with Hotwire (Turbo & Stimulus) and Tailwind CSS
• Familiarity with background job processing (Sidekiq, Delayed Job, etc.)
• Experience with Python and FastAPI - our data pipeline and some supporting services are built in Python, and you’d be expected to maintain and contribute to these alongside the Rails codebase
• Familiarity with Render or similar cloud infrastructure and deployment platforms
• Experience working in a startup or high-growth environment

Our Stack

• Backend: Ruby on Rails, PostgreSQL, Sidekiq
• Data & Services: Python, FastAPI
• Frontend: Hot…