Staff Software Engineer

Staff Full-Stack Software Engineer

X4 are working with a fast-growing healthtech company that's building innovative technology to transform how digital healthcare services are delivered. With a strong focus on scalable software and AI-driven solutions, the business is continuing to invest in its engineering capabilities as it expands its platform and develops new products.

This is an opportunity to join a growing technology team where you'll have real influence over architectural decisions, product development and the wider engineering roadmap. As a Staff Full-Stack Software Engineer, you'll work across front-end, back-end, cloud infrastructure and AI integration, helping build reliable, secure and scalable applications while setting technical standards for the wider team.

You'll combine hands-on engineering with technical leadership, working closely with product and engineering colleagues to turn ambitious ideas into production-ready solutions.

Key Responsibilities

• Lead the design and development of scalable, customer-facing applications, taking ownership of technical decisions from initial design through to production.
• Develop and evolve front-end applications using React, Next.js and modern JavaScript/TypeScript frameworks.
• Design and maintain back-end services, APIs and system architecture using Node.js and Python, including FastAPI.
• Own architectural decisions across AWS and/or Azure infrastructure, ensuring services are secure, reliable and built to scale.
• Drive improvements to CI/CD pipelines, deployment processes and infrastructure automation, promoting consistent engineering practices.
• Lead the integration of large language models (LLMs) and machine learning capabilities into production applications, using providers such as OpenAI, Anthropic, Gemini and open-source models.
• Design robust REST and GraphQL APIs and establish best practices around performance, security, maintainability and system reliability.
• Make informed decisions around database architecture, data modelling and application performance across relational and NoSQL technologies.
• Work closely with product management to translate business requirements into technical solutions and influence the platform's technical roadmap.
• Provide technical guidance to other engineers through code reviews, design discussions and knowledge sharing, helping raise engineering standards across the team.

Essential Experience

• 8+ years of professional software engineering experience, with a strong background in full-stack development and customer-facing applications.
• Extensive experience with JavaScript/TypeScript and modern front-end frameworks, particularly React, Next.js or TanStack.
• Strong server-side development experience with Node.js and Python, ideally including FastAPI.
• Proven experience designing and evolving scalable software architectures, with the ability to make sound technical decisions across the full stack.
• Hands-on cloud engineering experience with AWS and/or Azure, including services such as EC2, Kubernetes, Lambda, S3 and RDS, or their Azure equivalents.
• Strong experience building secure, scalable REST and GraphQL APIs.
• Experience working with relational and NoSQL databases, including PostgreSQL, DynamoDB or similar technologies.
• Practical experience integrating LLM APIs into production applications, with an understanding of prompt engineering, RAG, agent-based workflows and context window management.
• Experience with version control and engineering collaboration tools such as GitHub, Bitbucket, Jira and Confluence.
• The ability to take ownership of complex technical challenges, balance short-term delivery with long-term architecture and operate effectively in a fast-moving environment.

Desirable Experience

• Experience designing and maintaining CI/CD pipelines using GitHub Actions, Bitbucket Pipelines or similar tools.
• Strong knowledge of Infrastructure as Code, including Terraform, Pulumi or AWS CDK.
• Previous experience in healthtech or another regulated or data-sensitive environment, particularly working with protected health information (PHI).
• Experience building AI-powered products or introducing LLM capabilities into established software platforms.
• A background in a startup or scale-up where you've helped evolve architecture, establish engineering practices and support rapid product growth.

If you're interested in hearing more about the opportunity, please reach out to .