Java Fullstack Engineer - London (Hybrid) - Inside IR35

JOB TITLE: Principal/Lead Java Software Engineer (Hands-On)

LOCATION: London - Hybrid - 3x days a week onsite

DURATION: 6 - 12 Months Rolling

RATE: £400 per day, all inclusive

THIS PROJECT IS INSIDE IR35

We are looking for a highly technical, hands-on Principal-level Java Engineer to take ownership of the strategic technical direction for a critical automation platform. This is not a pure management role - you will be in the code daily, leading Scrum teams, refactoring Legacy systems, and acting as the ultimate technical gatekeeper for design and code quality.

If you are already using AI-powered coding tools daily to accelerate delivery and have deep experience with modern version control (including JJ), this role will play to all your strengths.

Key Responsibilities

• Own the overall technical roadmap and strategic direction for the platform.
• Design end-to-end solutions (Back End to Front End) using cutting-edge technologies and industry best practices.
• Get hands-on daily - refactoring Legacy applications, shipping new features, and bolstering existing software.
• Lead the Scrum process - build and prioritise the development backlog to deliver high-impact automation solutions.
• Act as the principal sign-off authority for all technology choices, design documents, and code reviews.
• Mentor and guide multiple Scrum teams, acting as the go-to technical expert for the entire department.

Essential Skills & Experience (Must-Haves)

• Extensive experience developing and deploying modern development methodologies at scale
• Extensive experience with Java 8+ (ideally 17+), REST API best practices, and SQL optimisation
• Extensive experience with modern version control (Git; JJ)
• Demonstrable Agile experience (Scrum or Kanban)
• Demonstrable experience leveraging agentic code harnesses for planning, code generation, quality enforcement, and delivery
• Experience contributing to and delivering software architectures for hand-off and implementation
• Experience with modern automated testing (Pact; TDD; BDD) and CI/CD pipelines

Nice-to-Have (Bonus Skills)

These are not essential, but candidates with any of the following will stand out:

• Some exposure to Legacy web application frameworks (eg, Zk or Django).
• Some experience creating and delivering network automations (eg, using Ansible, Python scripts, or similar).

About You

You are a Principal/Staff-level engineer who is equally comfortable white-boarding a high-level system architecture and drilling down into a complex SQL query or a tricky Git/JJ merge conflict.

You are passionate about leveraging AI to make your team faster and more efficient, and you have the maturity to be the final decision-maker on technology and code quality.