2,666 Senior Backend Developer jobs in the United Kingdom

About Us

Earnly is a FinTech startup on a mission to simplify financial management and empower individuals and businesses with real-time clarity on their money. We’re developing a new platform that makes financial insights accessible, transparent, and stress-free. As an early member of our team, you’ll have the opportunity to directly shape the product, culture, and future of the company.

About You

You thrive in dynamic environments where no two days are the same, motivated by big goals and the satisfaction of building something meaningful from the ground up. Startups bring tight deadlines, shifting priorities, and lean resources, but you embrace the challenge, staying focused under pressure, taking ownership, adapting quickly, and pitching in wherever needed.

The Role

We’re looking for talented backend developer with proven commercial experience to help us build the core infrastructure that shall power our entire platform. You’ll be responsible for designing, developing, and maintaining secure, scalable APIs, data processing pipelines, and backend integrations with third-party services like Stripe, PayPal, and Open Banking providers.

Key Responsibilities:

• Build and maintain robust RESTful APIs for mobile and web clients.
li>Design and manage databases built in MongoDB and SQL Server to store, query, and aggregate user financial data.
• Develop data ingestion pipelines to process real-time and batch data from external services.
• Optimize backend performance and ensure application scalability and resilience.
• Build authentication and authorization flows, following best practices for fintech-grade security.
• Write unit and integration tests, participate in code reviews, and contribute to continuous improvement.
• Collaborate closely with frontend/mobile engineers, product managers, and founders in agile development cycles.
• Contribute to infrastructure decisions (e.g. Docker, container orchestration, cloud services).

Skills & Experience You’ll Need

< i>3+ years’ experience in backend development (ideally in a startup or SaaS environment). < i>Proficient in .Net, Core 8, Razor Pages and Bootstrap 5 for UI.
• Experience with databases such as MongoDB and SQL Server, including schema design, indexing, and performance tuning.
• Familiarity with cloud platforms like Azure (we use Azure).
• Experience with containerization tools (Docker, Docker Compose) and deployment pipelines.
• Strong understanding of API design, versioning, and security (OAuth, JWT, API tokens).
• Comfortable working with Git, agile methodologies, and CI/CD practices.
• A good understanding of data protection, GDPR, and fintech security requirements.

Nice to Have

• Exposure to event-driven architecture or message queues (e.g. Kafka).
• Experience integrating

About Us

Earnly is a FinTech startup on a mission to simplify financial management and empower individuals and businesses with real-time clarity on their money. We’re developing a new platform that makes financial insights accessible, transparent, and stress-free. As an early member of our team, you’ll have the opportunity to directly shape the product, culture, and future of the company.

About You

You thrive in dynamic environments where no two days are the same, motivated by big goals and the satisfaction of building something meaningful from the ground up. Startups bring tight deadlines, shifting priorities, and lean resources, but you embrace the challenge, staying focused under pressure, taking ownership, adapting quickly, and pitching in wherever needed.

The Role

We’re looking for talented backend developer with proven commercial experience to help us build the core infrastructure that shall power our entire platform. You’ll be responsible for designing, developing, and maintaining secure, scalable APIs, data processing pipelines, and backend integrations with third-party services like Stripe, PayPal, and Open Banking providers.

Key Responsibilities:

• Build and maintain robust RESTful APIs for mobile and web clients.
li>Design and manage databases built in MongoDB and SQL Server to store, query, and aggregate user financial data.
• Develop data ingestion pipelines to process real-time and batch data from external services.
• Optimize backend performance and ensure application scalability and resilience.
• Build authentication and authorization flows, following best practices for fintech-grade security.
• Write unit and integration tests, participate in code reviews, and contribute to continuous improvement.
• Collaborate closely with frontend/mobile engineers, product managers, and founders in agile development cycles.
• Contribute to infrastructure decisions (e.g. Docker, container orchestration, cloud services).

Skills & Experience You’ll Need

< i>3+ years’ experience in backend development (ideally in a startup or SaaS environment). < i>Proficient in .Net, Core 8, Razor Pages and Bootstrap 5 for UI.
• Experience with databases such as MongoDB and SQL Server, including schema design, indexing, and performance tuning.
• Familiarity with cloud platforms like Azure (we use Azure).
• Experience with containerization tools (Docker, Docker Compose) and deployment pipelines.
• Strong understanding of API design, versioning, and security (OAuth, JWT, API tokens).
• Comfortable working with Git, agile methodologies, and CI/CD practices.
• A good understanding of data protection, GDPR, and fintech security requirements.

Nice to Have

• Exposure to event-driven architecture or message queues (e.g. Kafka).
• Experience integrating

Principal Backend Developer (C# / .NET / Playwright)

The Opportunity

This is a career-defining role for a Principal Backend Developer who wants to be at the forefront of a growing SaaS organisation. You'll be joining a company that's scaling rapidly, building innovative products that make a real difference to its customers. This role offers the chance to take ownership of backend systems, shape best practice, and mentor the next generation of engineers.

The Role

You'll provide technical leadership across backend development, ensuring systems are robust, scalable, and future-proof. Working closely with product owners, testers, and front-end teams, you'll bring engineering excellence into every decision. With a stack centred on C#, .NET, cloud services, and automation frameworks, you'll be both hands-on in coding and guiding others to deliver their best work.

Day-to-day responsibilities

• Architect and build scalable backend services in C# / .NET
• Drive adoption of clean coding practices, design patterns, and SOLID principles
• Mentor engineers, fostering a culture of growth, learning, and high performance
• Collaborate with product owners to refine requirements and translate them into technical solutions
• Integrate automation testing (Playwright) and CI/CD pipelines to ensure code quality
• Lead technical discussions, setting direction on tools, frameworks, and approaches
• Troubleshoot and resolve complex technical challenges across backend services
• Optimise system performance and ensure resilience across platforms
• Review code and guide engineering standards across the team
• Contribute to product strategy by aligning technical roadmaps with business goals

What you bring to the team

• Strong experience developing backend systems with C# and .NET
• Deep knowledge of cloud environments (Azure preferred)
• Experience in designing APIs and microservices at scale
• Solid understanding of automation testing tools (Playwright desirable)
• Leadership experience - mentoring, coaching, and guiding engineering teams
• Strong problem-solving skills with an eye for performance optimisation
• Enthusiasm for delivering quality solutions in a SaaS environment

Send your CV now to (url removed)

50249MS

INDMANS

Senior Backend Developer

Capital Pay Software Solutions Ltd

• Promoting world class

The Opportunity

We're looking for a talented Senior Backend Developer to join a purpose-driven tech team that creates solutions making a real difference in people's lives. This is more than just a job, it's a chance to shape systems that support individuals and organisations across the UK and Ireland.

The Role

As a Senior Backend Developer, you'll be a founding member of a newly formed cross-functional engineering team. You'll play a key role in setting the tone for the team's culture, practices, and success. Your technical expertise will shape our architecture and support business-critical applications.

This is a highly collaborative role suited to someone with a passion for software craftsmanship and continuous improvement.

Key Responsibilities

• Enhance features and functionality of core products
• Design and implement scalable backend systems using C# (.NET 5+ preferred)
• Write clean, maintainable, and testable code using TDD/BDD principles
• Create and maintain RESTful and GraphQL APIs
• Collaborate with POs, BAs, and stakeholders to define solutions
• Mentor junior developers and promote best practices
• Drive improvements in development processes and tools

What You Bring

• 5+ years of backend development experience
• Expertise in C#, .NET (preferably .NET 6+), and SQL Server
• Deep understanding of SOLID and OOP principles
• Skilled in Git, Unit Testing (NUnit), and API development
• Familiarity with CI/CD pipelines and agile methodologies
• Strong communication and problem-solving skills
• Desire to grow within a dynamic and evolving team

Why Join?

This is an incredible opportunity to make your mark in a company that prioritises purpose, innovation, and professional growth. You'll be part of a team where your ideas are welcomed, your development is encouraged, and your work truly matters.

Ready to build something that helps others-and builds your career in the process? Apply today.

48954MS

INDMANS

SThree are pleased to announce we're recruiting for a talented Senior Java Backend Developer to join & guide our excellent team based in our fantastic office space located in 8 Bishopsgate, London.

SThree are building a new candidate digital experience to manage the interactions that candidates and contractors have with SThree. The first part of this journey is to build a contractor onboarding portal to streamline the process from a candidate placement to onboarded contractor. This will then be extended to provide functionality to manage active placements, such as timesheets and expenses.

This role will design, develop, test and support capabilities in our digital experience platform to create competitive advantage for SThree, as part of a small software development team.

About us

SThree is the global STEM-specialist talent partner that connects sought-after specialists in life sciences, technology, engineering and mathematics with innovative organisations across the world. We are the number one destination for talent in the best STEM markets: Recruiting highly skilled professionals and discovering life-changing jobs for the unsung heroes who will positively shape our future.

What are the day-to-day tasks?

• Hands-on design, development and testing of solutions, adhering to SThree's architectural principles, policies, and guidelines.
• Work with business stakeholders to understand opportunities and to design solutions that deliver the required outcomes.
• Work with other technology teams to design and deliver end-to-end capabilities.
• Integrate solutions with other systems in SThree's technology landscape, for example CRM and ERP systems.
• Provide support to users and resolve systems issues.
• Configure CICD pipelines to support continuous delivery.
• Maintain infrastructure-as-code to build environments and applications.
• Focus on automation across infrastructure, testing, deployment, operations, and security.
• Coach and mentor junior team members and promote knowledge sharing and collaboration across the team.

What skills and knowledge are we looking for?

• Extensive experience of building web applications on a Java technology stack.
• Experience of RESTful API design and implementation.
• Experience with test-driven development and test automation frameworks and tools.
• Experience of configuring CICD pipelines to support continuous delivery.
• Experience with infrastructure-as-code technologies such as Terraform.
• Experience of working in Agile software development teams and across the full software development lifecycle.
• Previous experience of building solutions using Liferay DXP would be beneficial.
• Good understanding of Azure Integration Services (API Management, Service Bus, Event Hub).
• Good understanding of Microsoft Identity Management solutions (Azure AD, Azure AD B2C).
• Good understanding of cloud computing architectures and fundamentals like security, performance, and scalability, with experience of working with cloud technologies in Azure.

Benefits for our U.K. teams include:

• The choice to work flexibly from home and the office, in line with our hybrid working principles
• Bonus linked to company and personal performance
• Generous 28 days holiday allowance, plus public holidays
• Annual leave purchase scheme
• Five days paid Caregiver/Dependant leave per annum
• Five paid days off per year for volunteering `
• Private healthcare, discounted dental insurance and health care cashback scheme
• Opportunity to participate in the company share scheme
• Access to a range of retail discounts and saving

What we stand for.

We're committed to ensuring for our colleagues, candidates and communities, that all processes are equitable, and everyone is treated with fairness and dignity where everyone belongs, is valued and is connected. If you need any assistance or reasonable adjustments in submitting your application, please let us know, and we'll be happy to help.

What we stand for.

We create community and deliver change that transforms the future for everyone. With this in mind, we're committed to ensuring for our colleagues, candidates and communities, that all processes are equitable and everyone is treated with fairness and dignity where everyone belongs, is valued and is connected.

If you need any assistance or reasonable adjustments in submitting your application, please let us know, and we'll be happy to help.