Ruby on Rails Developer

Fynity; Greater London; On-site; GBP 70,000 - 110,000; Full time

Job summary

Fynity is seeking a Senior Ruby Engineer to maintain and evolve backend systems that support live production environments. You’ll work on Rails applications, optimize databases, and integrate with external services to ensure reliability and scalability.

You’ll collaborate with Product, Platform, and Engineering teams to improve backend architecture, observability, and deployment confidence while owning critical live systems.

Qualifications

• Strong experience with Ruby on Rails in production environments.
• Solid understanding of object-oriented design and Rails architecture.
• Experience building scalable backend services and APIs.

Responsibilities

• Maintaining and evolving Ruby on Rails applications supporting core operations.
• Designing and building scalable backend services and APIs.
• Writing clean, tested code and improving platform reliability.

Skills

Ruby on Rails

PostgreSQL

AWS

Docker

REST APIs

Redis/Sidekiq

CI/CD

Observability

Agile

Testing

Tools

Git

GitHub

Job description

The opportunity:

We’re looking for a Ruby on Rails Engineer to join a growing technology business building operational SaaS platforms used within large-scale, real-world environments.

This role sits within a backend engineering team responsible for maintaining and evolving systems that support live operational workflows. You’ll work on modern Ruby on Rails applications that process high volumes of transactional activity, integrate with external systems, and support business-critical operational processes.

The environment is fast-paced and product-focused, with a strong emphasis on reliability, scalability, and engineering quality. You’ll work closely with Product, Platform, and Engineering teams to improve backend systems, strengthen operational stability, and support ongoing platform growth.

This is a hands-on engineering role with ownership across backend services, integrations, and production systems. It would suit someone who enjoys solving complex backend challenges, improving platform reliability, and working collaboratively across technical teams.

What you’ll be doing:

As a Senior Ruby Engineer, you’ll help maintain and evolve backend systems that support operational workflows and live production environments.

Key responsibilities include:

• Maintaining and improving Ruby on Rails applications supporting core operational processes


• Designing, building, and maintaining scalable backend services and APIs


• Writing clean, maintainable, and well-tested code


• Supporting platform reliability, scalability, and long-term maintainability


• Managing and improving integrations with third-party systems and APIs


• Optimising PostgreSQL database performance and background job processing


• Supporting AWS-based deployments and CI/CD processes alongside Platform teams


• Investigating, troubleshooting, and resolving production issues


• Improving monitoring, observability, and deployment confidence


• Collaborating closely with frontend, mobile, and product teams


• Contributing to backend architecture improvements and technical documentation


• Supporting continuous improvement across engineering standards and delivery practices


• Taking ownership of systems that directly support live operational environments

What we’re looking for:

• Strong commercial experience with Ruby on Rails within production environments


• Strong understanding of object-oriented programming and Rails architecture


• Experience building and maintaining scalable backend systems and APIs


• Strong PostgreSQL experience, including complex queries and performance optimisation


• Experience with Redis and Sidekiq for background job processing


• Experience working with REST APIs, JSON serialisation, and authentication methods such as JWT or SSO


• Experience working with AWS-based infrastructure


• Experience using Docker within development or production environments


• Experience troubleshooting and supporting live production systems


• Strong debugging and problem-solving capabilities


• Experience working within existing codebases and improving legacy functionality


• Strong communication and collaboration skills


• Experience working within Agile environments using Git/GitHub


• Experience working with SOAP/XML integrations


• Experience migrating serverless components into Rails applications


• Familiarity with Vue.js


• Experience supporting mobile applications or mobile-focused backend services


• Experience within regulated industries or operational B2B SaaS environments


• Experience improving CI/CD pipelines and deployment reliability


• Open-source contributions or technical blogging experience

About you:

• You enjoy solving complex backend engineering challenges


• You’re comfortable working across live production systems and operational platforms


• You care about reliability, scalability, and maintainability


• You take ownership and communicate proactively


• You enjoy collaborating across engineering, product, and platform teams


• You’re pragmatic, adaptable, and delivery-focused


• You thrive in fast-moving environments where engineering quality matters