Senior Software Engineer (Data Ingestion Platform)

Who we are

4C Strategies builds organisational readiness and military training management software for clients in over 70 countries. Our flagship product, Exonaut®, is used by NATO and allied forces to plan, run and evaluate exercises in real time. Our consultants and engineers work alongside armed forces across the UK, Europe, North America and beyond to deliver training and exercise management solutions.

Why it matters

Deterrence works only when a capability is real, and a capability is only real once it has been trained and tested under conditions close to the ones it would face. This is about making sure the organisations that would hold the line are ready.

Why Join 4C Strategies

If you're happiest when the path isn't drawn yet, this is a rare chance to own hard, open problems on a large, multi-year programme — real scale, real production systems, and the freedom to shape how they're built — with a collaborative team to figure the hard parts out alongside you. You'll work alongside experienced engineers and military specialists, with the individual-contributor track valued as highly as management, so you can grow without leaving the code behind.

The work matters: what you build helps armed forces, public safety and resilience organisations train, prepare, and respond. If you want senior-level ownership on systems that are used in earnest — not a backlog ticket factory — this is that role.

How to apply

To apply, click the Apply today button and submit your CV. A short cover note on your experience and motivation is welcome but not required. We review applications on a rolling basis, so please apply as soon as you can.

4C Strategies is an equal opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all employees.

What we're building

We're building the data ingestion platform behind large-scale training exercises: a service that takes traffic from simulation federations, unmanned-system sensor networks and real-world sensor feeds, and turns it into one coherent stream that subscribing systems can act on. The bet is that these streams should be interpreted and mapped to an internal Ontology rather than re-interpreted by every product that needs it. So the hard part is as much modelling as engineering — deciding what those bytes actually mean, and then holding that meaning stable as the number of sources and consumers grows. The platform is greenfield, and you'll have real influence over its shape.

How we build

Modern Java. The principles are conservative on purpose: boring technology, simplicity over cleverness, in-process over distributed, shared-nothing over shared state, domain wrapped by ports and adapters. Redundancy is an architectural property, not an operational afterthought. Designs are argued from the problem, not from what a framework happens to make easy. Proposals go through RFCs; decisions are recorded in ADRs.

Two constraints shape most of what we do. Everything the platform produces must be traceable back to the raw feed and the exact configuration that produced it — a customer has to be able to replay an exercise and defend the result. And it has to run where exercises actually run: constrained hardware, intermittent connectivity, air-gapped sites, limited patch windows, secure by design and observability good enough for an operator in the field with no one to call.

You

Substantial engineering experience, opinionated about design, and comfortable arguing a position in writing. Sound judgement on reliability, security, performance, operations and cost is mandatory. Familiarity with simulation or sensor standards, IoT, geospatial mathematics or high-throughput ingestion is a real advantage — the domain is learnable, the principles less so. We'd also rather hear about how you simplified a distributed system rather than the one you built using multiple services.

The engineering team is small, but what we are building sits at the centre of the portfolio and draws the people who know this domain best — some of the strongest simulation and modelling expertise anywhere in the field is in this building, and closely engaged in what we're building. The bar is high. Your designs will be challenged, and you'll be expected to challenge back — including on scope, since most of the pressure on a platform like this comes as reasonable-sounding requests for one more special case.

Research shows some people only apply when they meet every requirement. If you don't tick every box but recognise yourself in much of the above, please apply anyway. We'd genuinely like to hear from you.

Security and citizenship

This role supports defence work, so the successful candidate must hold Swedish citizenship and pass Swedish security vetting (säkerhetsprövning). We will explain what the check involves early in the process rather than late — a requirement like this should never be a surprise at offer stage.

This requirement comes only from the security rules that govern defence work, not from personal preference.

How we hire

Every interview has a written script and a scored rubric, applied the same way to every candidate.

• Hiring Manager Screen — a conversation about your experience, how you work and what

you want next.

• System Design — a design discussion drawn from problems like the ones above.
• Programming — a hands-on session in a language of your choice (Java, C#, TypeScript, Python or Go).
• Culture Interview — how you collaborate, disagree and make decisions with others.
• Candidate Q&A — your time to interrogate us. We expect you to use it.

We then debrief as a panel and decide. We review applications on a rolling basis.

What you can expect from 4C Strategies

• Based in our Stockholm office: we expect you on site four days a week.
• Competitive salary, reviewed annually.
• Occupational pension (tjänstepension).
• Wellness allowance (friskvårdsbidrag).
• Healthcare insurance, including insurance for treatment.
• Parental pay.
• Vaccinations.
• A supportive, collaborative team building meaningful products for mission-critical work.