Full Stack Developer

UnknwnAI is looking for a Mid-Level Full Stack Developer to join our growing engineering team.

We develop modern software across SaaS, enterprise systems, healthcare technology, AI, integrations and business-critical applications. We work across a broad technology landscape, so we are looking for a developer with strong full-stack fundamentals who is comfortable working beyond a single framework or language.

This role is suited to someone with approximately 3+ years of professional software development experience who can contribute across frontend, backend, databases, APIs and integrations, while continuing to broaden their technical capabilities.

You should be comfortable taking a requirement or problem, understanding the wider context, designing an appropriate solution and seeing it through to a reliable production implementation.

What you will be doing:

• Designing, developing and maintaining full-stack applications
• Building modern frontend applications and user interfaces
• Developing backend services, APIs and business logic
• Designing and working with relational databases
• Writing efficient SQL queries and working with complex data
• Building integrations with third-party services, platforms and APIs
• Working across new applications as well as established production systems
• Taking features from initial requirements through development, testing and deployment
• Investigating application, API, database and infrastructure issues
• Debugging problems across multiple layers of a system rather than treating symptoms in isolation
• Contributing to application architecture and technical design decisions
• Improving performance, scalability, maintainability and reliability
• Implementing appropriate authentication, authorization and security controls
• Working with cloud-hosted applications and services
• Participating in code reviews and helping maintain engineering standards
• Writing clear, maintainable and reusable code
• Working collaboratively with developers and other members of the business
• Contributing ideas and proposing better technical approaches where appropriate
• Learning and working with unfamiliar technologies where a project requires them

Essential:

• Around 3+ years of professional software development experience
• Strong understanding of full-stack software development
• Good experience building modern web applications
• Strong programming fundamentals and understanding of software design principles
• Commercial experience with at least one modern frontend framework such as React, Next.js, Vue or Angular
• Experience developing backend applications, APIs or services
• Experience with backend technologies such as Node.js, TypeScript/JavaScript, C#/.NET, Python, Java or similar
• Strong understanding of REST APIs and application integrations
• Good knowledge of SQL and relational databases
• Experience with databases such as PostgreSQL, SQL Server, MySQL or similar
• Understanding of data modelling and relational database design
• Good knowledge of HTML, CSS and modern frontend development
• Experience using Git within a collaborative development environment
• Understanding of authentication, authorization and common web security principles
• Ability to debug problems across frontend, backend, API and database layers
• Ability to understand and work confidently within existing codebases
• Ability to translate business requirements into practical technical solutions
• Good understanding of application architecture and separation of concerns
• Strong problem-solving skills
• Good attention to detail and a disciplined approach to testing your own work
• Clear written and verbal communication
• Ability to work independently while remaining closely connected with the wider team
• Availability to work standard UK business hours

Our Current Technology Landscape:

Our technology varies between products and projects and will continue to evolve.

Technologies we currently work with include:

• TypeScript
• JavaScript
• Next.js
• React
• Node.js
• Tailwind CSS
• PostgreSQL
• Microsoft SQL Server
• Python
• C# / .NET
• REST APIs
• AWS
• Microsoft Azure
• Docker
• GitHub

Experience with every technology above is not required.

We are more interested in developers who have strong engineering fundamentals and can confidently move between technologies than someone whose experience is limited to one specific framework.

Useful Additional Experience:

Experience in any of the following would be beneficial:

• AWS or Microsoft Azure
• Cloud application architecture
• Docker and containerized environments
• CI/CD pipelines
• Automated testing
• Redis or other caching technologies
• RabbitMQ, message queues or event-driven systems
• Background jobs and asynchronous processing
• Microservices or distributed systems
• SaaS and multi-tenant application architecture
• Third-party API integrations
• E-commerce or marketplace integrations
• ERP or complex business management systems
• Healthcare technology
• AI and LLM integrations
• Authentication and identity platforms
• Performance optimization
• Application monitoring and logging
• Legacy system integration or modernization
• Secure software development
• High-availability or business-critical systems

What we expect from our Developer:

Ownership

You should be comfortable taking responsibility for a piece of work from beginning to end.

That includes understanding the problem, identifying dependencies, considering edge cases, implementing the solution, testing it properly and making sure the finished result actually meets the requirement.

Problem Solving

Software development frequently involves unfamiliar problems.

We expect developers to investigate issues properly, read documentation, understand existing code, test assumptions and work methodically towards the root cause.

Knowing everything is not expected.

Being capable of finding things out is.

Engineering Judgement

There is rarely only one way to build something.

We value developers who can consider maintainability, performance, security, complexity and delivery time before choosing an approach.

We also want people who are comfortable questioning an existing approach when they can explain why another solution would be better.

Communication

Our team works remotely, so communication is important.

We expect developers to:

• Raise blockers early
• Ask questions when requirements genuinely need clarification
• Communicate progress clearly
• Explain technical decisions
• Flag potential risks before they become problems
• Work collaboratively rather than disappearing into tasks

Quality

Speed matters, but not at the expense of reliability.

Developers should care about:

• Clean and maintainable code
• Appropriate testing
• Error handling
• Security
• Performance
• Edge cases
• Data integrity
• The wider impact of changes to a system

Adaptability

We do not want developers whose capability begins and ends with one framework.

Technology changes, projects have different requirements and sometimes the correct solution involves working in an unfamiliar part of the stack.

You should be willing and able to learn.

Why Join UnknwnAI

• Work across a broad range of technically challenging software
• Build both new applications and major functionality for established systems
• Gain exposure across frontend, backend, APIs, databases, integrations and cloud infrastructure
• Work with different technologies rather than being restricted to a single framework
• Have meaningful input into technical decisions
• Take genuine ownership of features and systems
• Work directly with a growing engineering team without unnecessary layers of management
• Develop experience across SaaS, enterprise software, healthcare technology, AI and complex business systems
• Join a growing company where your responsibilities and technical scope can expand significantly over time

How to Apply:

Please submit your CV along with your GitHub profile, portfolio or examples of relevant technical work, where available.

During the interview process, we will focus on what you personally contributed to previous projects, how you approach technical problems and how well you understand the systems you have worked on.

We are less interested in how many technologies appear on your CV but more interested on whether you can demonstrate strong engineering fundamentals, genuine hands-on experience and the ability to learn and solve problems effectively.