87 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 payment platforms like Stripe, PayPal, Plaid, or Open Banking.
• Exposure to Azure App Services.
• Knowledge of financial systems, accounting, or tax workflows.

What We Offer

This is an unpaid role; however, it provides a unique opportunity to join a fast-moving company that is committed to disrupting an outdated industry. While the position does not include a salary, it offers the potential to earn equity in the business, contingent upon meeting clearly defined milestones and deliverables.

• Equity within the business (granted after demonstrating ability and commitment)
• Remote & flexible working environment
• Training and development budget to support your growth
• The chance to join a FinTech startup at an early stage, where your input truly shapes the product and business

Requirements

• UK-based (remote OK), right to work in the UK.

Interested?

If you’re excited about building cutting-edge financial technology and want to be part of a growing startup, we’d love to hear from you. Click Apply Now!

We’re seeking a versatile Backend / AI Developer with hands-on experience delivering end-to-end solutions from concept to production. The ideal candidate brings strong expertise in Java (Spring Boot) and Python, with the ability to build scalable microservices, SaaS platforms, and AI-powered applications. You should be proficient in cloud platforms such as AWS and GCP, and experienced in API-first design, security best practices, and observability tools to ensure reliable, high-performing systems.

On the AI side, you have practical experience working with large language models (LLMs), prompt engineering, and frameworks like LangChain, with knowledge of advanced patterns such as Retrieval-Augmented Generation (RAG) and agent-based systems. A strong foundation in Agile SDLC practices is essential, along with familiarity in containerization, DevOps, and low-code/no-code platforms.

Experience across both backend and AI domains will enable you to seamlessly integrate advanced AI capabilities into scalable enterprise systems, making you a key contributor to building the next generation of intelligent, secure, and high-performance applications.

Backend / AI Developer – Key Skills & Competencies

Core Development:
Hands-on experience in taking solutions from concept to production, with strong expertise in Java (Spring Boot) and Python for backend and AI-driven application development.

Proficiency in building microservices, SaaS solutions, and API-first architectures to enable scalable, interoperable systems.

Frameworks & Tools:
Backend: Spring Boot (web, data, cloud, security), JUnit 5, Mockito, database integration.

AI: LangChain, Retrieval-Augmented Generation (RAG), MCP servers (as consumer and developer), and prompt engineering for LLM optimization.

Exposure to popular libraries and frameworks (Apache Commons, Guava, Swagger, TestContainers).

Architecture & Platforms:
Skilled in designing and deploying distributed systems on cloud hyperscalers (AWS, GCP).

Familiarity with containerization (Docker), CI/CD pipelines, DevOps practices, and Infrastructure as Code (IaC).

Experience with workflow/orchestration engines and agent-based architectures.

Scalability, Data & Observability:
Expertise in designing for scalability, performance, and extensibility across structured, semi-structured, and unstructured data.

Strong foundation in security best practices, with practical knowledge of logging, metrics, tracing, distributed debugging, and performance monitoring.

Awareness of AI application security and model safety considerations.

AI Development: 
End-to-end development of AI-powered solutions, from concept to production readiness.

Practical experience with LLMs and agentic AI, including LangChain integration, RAG pipelines, prompt engineering, and model consumption via APIs.

Ability to bridge backend and AI workflows, integrating advanced AI capabilities into scalable enterprise platforms.

SDLC & Agile Practices: 
Familiar with the Software Development Life Cycle (SDLC) and effective collaboration in Agile environments.

Ability to leverage low-code/no-code platforms for rapid solution delivery.

Nice to Have:
Knowledge of Domain-Driven Design (DDD) and schema-first development.

Experience designing plugin architectures and extensibility frameworks.

Exposure to frontend development (HTML5, CSS3, TypeScript, responsive UIs) for full-stack collaboration.

To apply, please submit your CV and daily rate expectation by clicking on the relevant links. If successful you will be contacted by one of our consultants within 3 working days. Unfortunately, due to the volume of applications we expect to receive for this role, if you do not hear from us within this time you should presume your application has been unsuccessful on this occasion.

Grassroots Recruitment is acting as a recruitment agency and a recruitment business in respect of this contract vacancy. Grassroots Recruitment is an equal opportunities employer and recruiter. We welcome applications from all sections of the community, regardless of age, race, sex, sexual orientation, marital status, religion or disability

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.

48954MSR1

INDMANS

Are you a developer who wants to build products that people genuinely love to use? Are you looking for a role where your features go live and immediately create engagement, excitement, and value for thousands of users?

I am currently partnering with a leader in the UK's digital entertainment space to find a creative and driven Full Stack Developer to join their mission. This is a fantastic opportunity to move beyond just being a coder and become a true product builder. You'll be joining a dynamic team where your voice is heard, your ideas are valued, and your code directly shapes the user experience from the ground up.

This Role Offers You the Chance To:

• Deliver Real Impact: You will develop core features for their flagship platform, directly influencing user engagement and satisfaction.

• Own Your Work: Take features from the initial brainstorming session right through to deployment, owning both the back-end logic and the front-end implementation.

• Solve Interesting Puzzles: Architect robust API integrations and elegant database structures designed to handle a growing user base.

• Craft Great Experiences: Collaborate closely with designers and product leads to ensure their platform is not only powerful and scalable but also a joy to use.

• Grow Your Skills: Contribute to a culture of continuous improvement, working with a modern stack and agile processes.

The Ideal Candidate Profile: My client is looking for a developer who is:

• An experienced PHP professional with proven success using the Laravel framework.

• Comfortable across the stack, with solid skills in HTML, CSS, JavaScript, and MySQL.

• A natural collaborator who thrives in a team environment but can drive their own projects forward.

• Passionate about writing clean, maintainable, and testable code.

• Excited by the challenge of building and scaling a user-centric product.

The Package & Benefits:

• Balanced Work Life: A hybrid model that combines focused remote work with collaborative office days (in-office Monday + two other days).

• Rewarding Your Contribution: A strong benefits package including a competitive salary, 22 days holiday (+ bank holidays), performance bonuses, and share options.

• A Vibrant Culture: You will join an ambitious, supportive team that celebrates success together.

If you're ready to make a tangible impact in your next role, I would love to hear from you.

My client is an equal opportunity employer, committed to fostering a diverse and inclusive workplace. All applications will be judged on merit and skill, regardless of background.

Ripple Recruitment is acting as an employment agency for this vacancy. Please note that due to the high volume of interest, we can only respond to shortlisted applicants. Thank you for your understanding.