Software Engineer Intern in London

Visa sponsorship is available for this role. We are looking for exceptional talent from anywhere in the world to join our team in London.

About Arctic Lake

We build sophisticated trading technology for tier 1 banks. We are small now, but we have big ambitions to become a major force in our industry over the next 2 years. We compete with the biggest HFTs and tech giants for the smartest computer science graduates in the world, but we are something different. We don’t offer the corporate gloss or the massive campus, but what we do offer is the rare chance to ship meaningful work to production across an unusually broad technical spectrum with very smart, humble people who care deeply about understanding how systems actually work. We don't have established playbooks for everything. We’re actively experimenting with how we work, how we grow, and how we solve problems. For the right person, our lack of rigid process in some areas isn’t a gap, it’s an opportunity to help build the company itself. Ideas are welcome, regardless of where they come from, and you’ll see the inner workings of a company that’s building itself while building its product. This is the perfect time to join us. You get the agility of a small team combined with the trajectory of a scaling business. You aren’t stepping into a static machine; you are helping to build the engine. As we grow, you grow - offering a speed of career progression that the much larger incumbent firms simply cannot match.

Over the course of your career at Arctic Lake, you might touch anything from bare-metal optimisation to high-level application logic. You could go deep in systems programming on one project, then own the full lifecycle of an internal tool that transforms how the team works. Throughout it all, you will rely on data analysis. We are an evidence-based company, and we expect everyone, regardless of their role, to back their ideas with evidence rather than intuition.

A Day at Arctic Lake

We are big believers in the power of being in the room. Learning by osmosis and creative serendipity aren’t optional for us. Sometimes we are loud and collaborative; sometimes we are heads-down and quiet. We value creativity and humility just as much as raw IQ, which means we have built a genuinely good group of people.

During your internship, you will probably work on one of the following projects:

• ALX Trading Engine: Low-latency processing for market data and order routing.
• Hardware Acceleration: FPGA-based system for offloading extremely time sensitive logic checks.
• DLT Solutions: Next generation of TradFi built on distributed ledger technology.
• Internal Tooling: A platform for coding challenges, and other tools that improve developer experience.

Who this is for

If you value depth over brand names, if you want real responsibility rather than tickets in a queue, and if you’re energised by a culture of constant iteration and active experimentation, this will suit you. We prioritise curiosity and learning velocity over perfect credentials. The work is intellectually demanding, the pace varies from "ship fast" to "optimise obsessively" depending on what the problem demands, and you’ll be surrounded by people who are genuinely invested in the quality of what we build.

⚠️ Who this is NOT for

You have "Main Character Energy." We are a team. We win together and we fix things together. If you view your colleagues as supporting actors in your story, or if you think certain tasks are "beneath" you, you won’t survive here. We filter for low ego and high empathy. You need a structured syllabus. We have a high ratio of juniors to seniors because we believe that engineers at the start of their careers are smart and capable and aren’t held back by limiting beliefs about how things “should” work. This is a feature, not a bug, but it comes with a cost: We do not have a traditional, hand-holding mentorship program. You will have access to brilliant senior engineers, but you have to drive the interaction. If you wait to be told what to learn next, you will stall. If you are the type to hunt for answers and pull knowledge from those around you, you will fly.

The Challenge: Our Technical Assessment

Note: To keep the playing field fair, our initial coding challenge is in Java. Don’t let this fool you, we are not exclusively a "Java Shop." We use Java for the test because it is a standard university language that allows us to test your logic and architectural thinking (and a lot of our stack is, in fact, in Java). However, once you are here, you will be exposed to a diverse tech stack including Python, TypeScript, SystemVerilog (for FPGAs), Raft, Kubernetes, DLT, Angular, and more.

The Package

Potential: A clear path to a permanent role after graduation. Compensation for permanent roles currently includes equity—a rare find in today’s tech environment.

Perks: Free snacks/drinks, weekly team lunches, 25 days holiday (plus bank holidays), annual retreat abroad, social events.

Think you might be one of us? Apply now!

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