Senior Backend Engineer (.NET & Python) in London

Who are Benifex? 💚💜 We are a fast-moving technology company, and one of the most successful providers of online reward and benefits solutions in the world. We believe that everyone deserves an exceptional experience at work, every day, and build workplace technology that makes this happen. Benifex’s mission is to build remarkable experiences that employees love. Today Benifex supports more than five million employees in over 3,000 organisations across more than 100 countries. To help us on our quest to be the best, we need brilliant people on board and that’s where you come in. 🚀

Why should you apply? 🌟

• Take a leading role in shaping Brain, Benifex's flagship AI product, and influence how we build AI-powered experiences for our customers.

• Own complex features end-to-end, driving technical decisions and delivering impact at scale.

• Expand your expertise across GenAI, cloud technologies and modern backend architecture while helping to evolve our AI-first engineering practices.

• Grow your career within a high-performing engineering organisation that invests in technical development, learning and progression.

Great benefits

💰 £70,000 - £90,000

💻 Tech setup of your choice (MacBook Pro or equivalent, monitors, etc.)

📚 £/€800 annual learning budget, plus two hours per week as ‘Focus Fridays’.

🤸 Flexible work – choose a working setup that works for you, our only ask is to see you once a month in the office and you must be based in the UK or Ireland.

💸 Full access to our comprehensive benefits package, including discounts from hundreds of high street brands, salary sacrifice schemes across Finance, Health, Tech, and more

✈️ 25 days holiday plus your local bank holidays

🎂 Your birthday off

❤️ Two half day wellbeing days

🩺 Healthcare cash plan to cover the costs of day-to-day healthcare

🧠 Employee Assistance Plan 24/7 365 support

🤒 Income Protection (75%) and life assurance (4x salary)

💰 Referral bonuses

🌟 Enhanced parental leave package - 26 weeks fully paid maternity leave and 4 weeks fully paid paternity leave

✈️ Work from Anywhere policy for 90 days

🏖️ Buy and Sell scheme for holidays

💳 £50 monthly allowance to spend on whatever takes your fancy, your very own Benifex card will be topped up at the start of each month!

Role Overview 🚀

We are looking for a Software Engineer with strong .NET and Python expertise and hands-on GenAI experience to help build and evolve Brain, Benifex's flagship AI platform. In this role, you will design, develop and deliver high-quality backend solutions that combine modern AI technologies with our established benefits platform. You will work closely with Product, Design and Engineering colleagues in a collaborative, distributed environment while contributing to our AI-first software development lifecycle. This is an opportunity to take ownership of impactful features, strengthen platform reliability and help shape the future of AI-native engineering at Benifex.

Responsibilities 🤘

• Design, develop and deliver new features for Brain, integrating AI capabilities with Benifex's wider platform.

• Build and maintain high-quality backend services and APIs using .NET and Python technologies.

• Take ownership of the code you ship, contributing to testing, troubleshooting and continuous improvement.

• Collaborate with Product, Design and Engineering teams to deliver customer-focused solutions.

• Improve platform reliability, observability, performance and security.

• Help evolve Benifex's AI-assisted development practices and support other engineers across the team.
  

What are we looking for? 🔎

• Commercial experience developing backend applications using C#, .NET/.NET Core, Python and SQL.

• Production GenAI experience, including technologies such as MCP, RAG, agent orchestration, evaluations and observability tooling.

• An understanding of responsible AI, software quality, performance and security best practices.

• Experience delivering features end-to-end within modern engineering environments.

• Exposure to CI/CD pipelines, containerisation and modern architecture patterns such as microservices and event-driven systems.

• Strong collaboration skills, a proactive mindset and hands-on experience working with AI coding assistants.

Bonus points

• Experience with Kubernetes, GCP, Google Pub/Sub, Kafka or Redis.

• Familiarity with Langfuse, Grafana, Prometheus or Terraform.

• Experience mentoring or supporting other engineers.

Even if you don't meet all of the requirements for this role, we encourage you to apply! We are looking for talented and passionate individuals who are eager to learn and grow.

Our interview process

📞 Initial interview with the Talent team
⏳ Interview with the hiring manager
🤩 Final interview with a senior team member/director

We are a proud member of the Disability Confident employer scheme.

If you require any reasonable adjustments at any stage during the recruitment process, please let us know with your application.