Lead Java Engineer

We are hiring a Lead Java Engineer, and we are highly selective about who joins the team. We are looking for an engineer who takes full ownership of the systems they design: the architecture, the implementation, and how that code behaves in production. The role carries real autonomy, and with it the expectation that you resolve problems rather than escalate them.

You will be joining one of the fastest-growing companies in one of the most demanding domains in software, working on a platform used by airlines everyone knows.

The Role

You will work alongside our engineering and product teams as an equal partner, shaping what we build, how it is architected, and which trade-offs we are prepared to accept. You will own the technical surface end to end: domain and data modelling, service design, performance under load, correctness in a domain where errors are costly, and the AI-assisted workflows that allow us to deliver quickly without compromising stability.

This is a hands-on lead role. Your influence derives from the quality of your design decisions and from the improvement of the engineers who work alongside you.

We operate with a people-first mindset: First Who, Then What . We hire exceptional people, give them ownership, and determine the path forward together.

About Us

Optifly is an end-to-end aviation scheduling and optimisation platform purpose-built for airline schedule planners, operations managers, and commercial teams. It enables airlines to plan, build, optimise, and analyse flight schedules across an entire season.

Headquartered in Ireland, Optifly is powered by a world-class engineering team with deep expertise in aviation technology, optimisation, and large-scale scheduling systems.

Optifly is a scheduling partner for some of the world's leading airlines, including Wizz Air, Transavia, Eurowings, and others.

Responsibilities

Own solution architecture for a busy, multi-tenant platform in which a single user action may affect hundreds of thousands of records, including the data model, transaction boundaries, batching strategy and failure behaviour.

Remain accountable for those architectural decisions once they are operating in production.

Contribute production Java code daily within a large, established codebase built on modern Java and Spring Boot.

Establish and enforce performance standards supported by measurement rather than assertion, covering query plans, batched writes, memory behaviour and lock contention.

Raise the engineering standard across the team through code review, pairing, and written design documentation.

Diagnose production issues independently using logs, traces and metrics, and establish root cause before escalating.

Apply AI-assisted tooling where it demonstrably improves design exploration, code generation, refactoring and debugging, and recognise where it does not.

Set the technical direction of the systems you own.

Who This Role Is Not For

This role is unlikely to suit you if:

You require a detailed specification before beginning. Direction here is set, not received.

You need a prolonged period before becoming productive. We operate at pace.

Your experience is limited to low-traffic applications. Scale is a routine consideration in this codebase.

You regard architecture primarily as documentation. We expect you to state the trade-off you made and what it cost.

You interpret seniority as control over the codebase rather than the development of the people working in it.

You have an interest in AI tooling but do not yet use it in your daily work, or cannot articulate where it fails.

You are seeking a short-term or freelance engagement. This is a long-term appointment.

Hiring Process

We keep the process short and communicate the outcome of each stage.

CV screening: We review every application, including the answers to the questions below. Those answers carry equal weight to the CV.

Practical task: Shortlisted candidates receive a task timeboxed to four hours. We assess reasoning and judgement rather than completeness.

Introductory call: An initial conversation with the hiring manager covering your submission, your background, and what you are looking for.

Technical interview: A detailed session with our engineering team covering architecture, trade-offs, an algorithmic exercise, and your reasoning under realistic constraints.

Team fit: A concluding conversation with the team to confirm the appointment is right for both sides.

Compensation & Commitment

Compensation is competitive and reflects demonstrated impact. This is a full-time appointment with a long-term trajectory.

Required Qualifications

B2-level English or higher.

Substantial hands-on experience with Java and Spring Boot in production systems.

Demonstrable experience designing solution architecture for busy, data-intensive systems, and operating those systems afterwards.

Depth in relational databases: modelling, query performance, transactions, and behaviour at volume.

Experience in a technical lead capacity.

Experience delivering within large, long-lived products.

8+ years in high-performing enterprise environments. We prioritize deep architectural impact over titles, but the system complexity demands proven seniority.

Desirable:

Demonstrable mentoring experience: engineers whose capability improved measurably while working with you.

Additional Information

Applications must include answers to the following questions. This is a prerequisite for consideration.

Which of the criteria described in this post best matches your experience, and why?

Describe a system you designed that was required to handle significant load or data volume. What was the constraint, what did you decide, and what did that decision cost you?

Which coding agent tool do you prefer, and how would you use it to deliver a non-trivial feature end to end in a large Java and Spring codebase you have not seen before? Where would you decline to rely on its output?

Are you available to work full-time, comfortable working eight hours per day, attending all meetings, and operating as a full-time employee? The role additionally requires attendance in the office three days out of five. Please confirm that this arrangement is acceptable.