Senior Backend Engineer - .Net

About us

We are champions of rail, inspired to build a greener, more sustainable future of travel. Trainline enables millions of travellers to find and book the best value tickets across carriers, fares, and journey options through our highly rated mobile app, website, and B2B partner channels.

Great journeys start with Trainline

Now Europe’s number 1 downloaded rail app, with over 135 million monthly visits and £6.3 billion in annual ticket sales, we collaborate with 270+ rail and coach companies in over 40 countries. We want to create a world where travel is as simple, seamless, eco-friendly and affordable as it should be.

Today, we're a FTSE 250 company driven by our incredible team of over 1,000 Trainliners from 50+ nationalities, based across London, Paris, Barcelona, Milan, Edinburgh and Madrid. With our focus on growth in the UK and Europe, now is the perfect time to join us on this high-speed journey.

Introducing the Trainline Cloud Native Developer Experience Team

At Trainline, we're evolving the platform that powers millions of journeys across Europe. As part of our Cloud Native Acceleration Programme, we're modernising our backend services to create a more scalable, resilient and efficient engineering platform. This programme is about more than migrating workloads. It's an opportunity to redefine how .NET services are built, deployed and operated, helping teams deliver faster while improving reliability and reducing operational complexity.

As a Senior C# Engineer, you'll play a key role in shaping our cloud-native engineering standards. Working closely with Platform Engineering, Infrastructure, Security and product development teams, you'll modernise existing services, build reusable patterns and develop automation that accelerates engineering across the organisation. Your work will have a lasting impact on both the developer experience and the resilience of our platform.

Success in this role is measured not only by modernising services, but by raising engineering capability across Trainline through reusable tooling, technical leadership, collaboration and the adoption of cloud-native engineering practices and by the ability to collaborate across the organisation.

In this role as the Senior C# Engineer, you will...

• Modernise existing .NET services by containerising applications for Amazon ECS, removing legacy infrastructure dependencies and optimising services for cloud-native operation.

• Design and build resilient distributed systems by improving health checks, fault tolerance, observability and runtime behaviour to enhance service reliability and reduce operational incidents.

• Define and evolve the .NET migrations by creating reusable service templates, engineering standards and best practices covering dependency injection, configuration, logging, monitoring and deployment.

• Develop automation and AI-assisted tooling that accelerates cloud migration by analysing existing services, identifying modernisation opportunities and generating infrastructure and deployment scaffolding.

• Optimise containerised workloads to improve performance, resource utilisation and scalability, helping teams deliver efficient, cost-effective services at scale.

• Partner with engineering teams across Trainline to drive adoption of cloud-native engineering practices, influence technical direction and build consensus around modernisation approaches that enable successful service migrations.

• Contribute to the continuous improvement of CI/CD pipelines and deployment processes, enabling faster, safer and more consistent software delivery.

• Champion cloud-native engineering through technical leadership, documentation, design reviews, demos, mentoring and engineering community engagement, helping teams adopt consistent engineering practices with confidence.

We'd love to hear from you if you have...

Core skills

• Strong professional experience developing applications with C# and .NET, alongside a solid understanding of software engineering principles and modern backend architecture.

• A good understanding of distributed systems, including resilience patterns, observability, scalability and performance optimisation.

• Experience designing reusable engineering patterns, frameworks or shared libraries that improve consistency and developer experience across multiple teams.

• Strong collaboration and communication skills, with the ability to work effectively across engineering teams and influence technical decisions through partnership and expertise.

• A continuous learning mindset and a passion for improving engineering practices, modernising legacy systems and delivering measurable business impact.

Infra and Cloud Native experience

• Experience developing and maintaining Infrastructure as Code using Terraform (or equivalent), alongside a strong understanding of CI/CD pipelines and modern software delivery practices.

• Experience building and operating cloud-native applications using containers and orchestration technologies within AWS and Amazon ECS.

AI experience

• Experience using AI-assisted engineering tools to improve productivity, quality and software delivery, while applying sound judgement to validate outputs.

• You're curious about the rapidly evolving AI landscape and can identify practical opportunities to apply AI to engineering workflows, automation and developer experience - ideally through first hand experience.

Communicating and Influence

• A track record of influencing technical decisions across engineering teams through collaboration, clear communication and technical credibility.

• Strong communication and collaboration skills, with the ability to explain technical concepts to diverse audiences, build trusted relationships and help drive organisational adoption of engineering standards and best practices.

More information:

Enjoy fantastic perks like private healthcare & dental insurance, a generous work from abroad policy, 2-for-1 share purchase plans, an EV Scheme to further reduce carbon emissions, extra festive time off, and excellent family-friendly benefits.

We prioritise career growth with clear career paths, transparent pay bands, personal learning budgets, and regular learning days. Jump on board and supercharge your career from day one!

We're operating a hybrid model and ask that Trainliners work from the office a minimum of 60% of their time over a 12-week period. We also have a 28-day Work from Abroad policy.

Our values represent the things that matter most to us and what we live and breathe everyday, in everything we do:

• Think Big - We're building the future of rail

• ✔️ Own It - We focus on every customer, partner and journey

• Travel Together - We're one team

• ♻️ Do Good - We make a positive impact

We know that having a diverse team makes us better and helps us succeed. And we mean all forms of diversity - gender, ethnicity, sexuality, disability, nationality and diversity of thought. That's why we're committed to creating inclusive places to work, where everyone belongs and differences are valued and celebrated.

Interested in finding out more about what it's like to work at Trainline? Why not check us out on LinkedIn , Instagram and Glassdoor !