Senior Software Engineer

Build the Future of Workplace Collaboration at Thomas

At Thomas, we're redefining how teams connect and collaborate. Our AI-driven platform, Thomas Connect, delivers deep behavioural insights that help teams work smarter, not harder.

We're looking for a Senior Software Engineer to help us build scalable, high-performance applications that transform the modern workplace. If you're excited about solving complex problems, working with cutting-edge tech, and driving innovation in a fast-paced SaaS environment, read on.

Is This Role Right for You?

We're not just building software, we're revolutionising how teams collaborate. As a Senior Software Engineer, you'll play a key role in shaping our AI-powered platform, Thomas Connect, helping to build modern, scalable web experiences that drive real business impact.

We're looking for someone who is analytical, innovative, and collaborative, with a passion for high-quality software, strong engineering principles, and methodical problem-solving. If you enjoy the balance between engineering excellence and elegant design, this is the role for you.

What You'll Do

• Develop & scale modern web applications using C#, .NET Core, CosmosDB, Redis
• Design, build, and refine RESTful APIs to enable seamless data integration
• Create engaging, high-performance frontend experiences using React, JavaScript, HTML, and CSS
• Influence system architecture, contributing to design discussions and proposing innovative solutions
• Lead and participate in code reviews, promoting best practices and high engineering standards
• Collaborate with UX Designers, Product Managers, and Engineers to deliver impactful new features
• Optimize automated testing using tools like Jest, Playwright, and Vitest
• Mentor and support junior engineers, fostering a culture of learning and collaboration
• Continuously improve software quality, security, and performance

Requirements

What We're Looking For

Must-Have Experience:

• Strong C# skills with .NET Core and cloud-based backend technologies (CosmosDB, Redis)
• Expertise in JavaScript, React, and modern frontend technologies
• Experience building RESTful APIs and responsive, mobile-first web applications
• Deep understanding of asynchronous JavaScript and core browser concepts
• Experience with test automation tools (Jest, Playwright, Vitest)
• Agile mindset - comfortable working in fast-paced, iterative development cycles

Nice-to-Have Skills (Bonus!):

• Experience working with Docker, Kubernetes, Microsoft Azure, or AWS
• Familiarity with microservices architecture

Join us and help shape the future of workplace collaboration. Apply now to be part of our journey!

Benefits

• Holiday - 25 days per annum, plus the opportunity to purchase up to an extra 5 days per annum through the salary sacrifice holiday buy scheme (plus an extra day off for moving house!)
• Early Finish Friday - Finish at 15:00 all year round
• Hybrid Working - primarily working from home with some days as agreed with the People Manager from the office
• An extra day off for your birthday and for moving house!
• Employment Assistance Programme - Access to Workplace Options which provides a complete support network that offers expert advice and compassionate guidance and is accessible 24 hours a day, 7 days a week, 365 days a year
• UK Healthcare - cash plan where members of Team Thomas can claim back for various healthcare appointments (including dental and optical)
• My Specialist GP - a private GP surgery located in Marlow, which is available for all members of Team Thomas to use for emergency on the day appointments, paid for by Thomas.
• Gym Membership - Thomas will either pay up to £28 per month towards gym membership at any nationwide gym, or £28 per month towards membership at The Marlow Club (a gym and swimming pool located close to the Marlow office)
• Perkbox - a communication, health & wellbeing, and discount portal, allowing members of Team Thomas to keep up to date with business news, access information on health & wellbeing offerings and access discounts on a wide range of retail products and leisure activities
• Personalised Feedback Session - with an enablement specialist to gain insight into own Thomas insights
• Dress down policy - other than for client facing meetings where appropriate
• Enhanced Maternity and Paternity Scheme
• A Salary Sacrifice Pension Scheme

Location: This role is based in the UK and aligned with our Marlow office