Principal Engineer

_{24th August, 2026}

We’re teaming up with Epsilon Retail Media on one seriously interesting engineering hire.
  
They’re looking for a Principal Engineer to join their Australian team (in Brisbane) - and this one is for the engineers who’ve reached the point in their career where the hardest problems are usually the most appealing.
  
Search and relevancy. Distributed systems. Performance and latency. Ad serving. Auction mechanics. Architecture that needs to work reliably at serious scale.
  
There’s plenty of technical meat on the bone, but what makes this role particularly interesting is the breadth of influence that comes with it.
  
This is one of Epsilon’s most senior individual contributor positions within the AU biz. You’ll help set architectural direction across a major part of the Retail Media platform, lead some of its trickiest technical initiatives and mentor other senior engineers - all without disappearing into a management role.

And importantly, you’ll still be an engineer.
  
You’ll stay close to the technology, get into the detail when it matters and remain genuinely accountable for whether the solutions you help design actually work.
  
So… who is Epsilon Retail Media?

Epsilon Retail Media builds technology that helps some of the world’s leading retailers create, manage and grow their own retail media businesses.
  
At its simplest, they’re helping retailers connect brands with customers at exactly the right point in the shopping journey. Underneath that sits a seriously sophisticated technology platform dealing with search, advertising, personalisation, measurement and huge amounts of real-time decision-making.
  
It means the engineering problems are rarely straightforward.
  
You’re balancing performance with cost. Speed with reliability. Immediate customer needs with long-term architecture. And increasingly, you’re working out where AI can genuinely make products and engineering better rather than simply adding it because everyone else is talking about it.
  
That’s exactly the kind of environment this Principal Engineer will step into.
  
THE GIG

You’ll take technical ownership across a major domain of the platform, working closely with Engineering, Product and Data Science to help shape both where the technology needs to go and how the team gets there.
  
There’ll be some properly difficult systems problems to solve, particularly across areas like search, relevancy, ad serving and advertiser performance. You’ll help teams work through architectural trade-offs, challenge assumptions and make pragmatic decisions that balance scalability, reliability, performance and commercial reality.
  
But Epsilon isn’t looking for someone who sees architecture as an endless collection of diagrams.
  
They want someone who can get under the hood.
  
Someone comfortable jumping into a codebase, building a prototype to prove an idea, investigating a performance problem or working alongside another engineer when the implementation gets particularly gnarly.

There’s also a strong product-thinking component to the role.
  
You’ll spend time understanding the problems retailers and advertisers are actually trying to solve, working with Product and Data Science to form hypotheses, test ideas and use evidence to guide what happens next.
  
Sometimes the right answer will be a sophisticated architectural change. Sometimes it’ll be a deliberately scrappy prototype that tells you whether an idea has legs before anyone spends six months engineering it beautifully.

Knowing the difference is a pretty important part of the job.
  
Your day will look a lil' like this…

• Own the architectural direction across a major domain of Epsilon’s Retail Media platform and help shape the longer-term technical roadmap.
• Lead the design and delivery of complex, high-impact engineering initiatives where the answer isn’t obvious from day one.
• Stay close to the code, particularly around prototypes, critical components and technically challenging problems.
• Work through performance, scalability, latency, reliability and cost trade-offs across distributed systems.
• Partner closely with Product and Data Science to connect technical decisions back to genuine customer and commercial outcomes.
• Help teams experiment intelligently, validate ideas early and learn before unnecessarily scaling solutions.
• Establish architectural patterns and engineering standards that can be reused across teams.
• Bring depth and healthy challenge to technical design and architecture discussions.
• Mentor Senior Engineers, helping grow the next layer of technical leadership across Epsilon.
• Help shape how modern engineering approaches, including AI-assisted development, are used effectively across the organisation.

And you?

There probably isn’t one perfect route into this role.
  
You might already be a Principal Engineer or Senior Staff Engineer inside a sophisticated SaaS or product business. Perhaps you’ve spent time as a technical founder or CTO and realised that the technology and product problems excite you considerably more than managing an organisation.
  
Whatever the title, you’ve built enough scar tissue to know that great engineering is rarely about finding the theoretically perfect answer.
  
It’s about understanding the problem properly, weighing the trade-offs and making the right decision for the environment you’re actually operating in.
  
You’ve probably become the person people pull into the room when something is particularly complicated. Not because you magically know everything, but because you know how to ask the questions that eventually get everyone somewhere useful.
  
The good stuff you'll bring

• Significant experience designing and operating complex backend or distributed systems.
• Deep systems-design capability across areas like scalability, latency, concurrency, reliability and performance.
• Strong backend engineering foundations, ideally across Java, Go or similarly capable modern languages.
• Experience making architectural decisions that have influenced multiple engineers, teams or products.
• Strong cloud experience and an understanding of operating software at meaningful scale.
• The ability to stay hands-on when the problem calls for it rather than treating implementation as somebody else’s job.
• Excellent judgement around technical trade-offs and the ability to communicate the reasoning behind your decisions.
• Experience mentoring senior engineers and influencing technical direction without relying on hierarchy.
• Strong product instincts and genuine curiosity about the customer problem behind the engineering work.
• A pragmatic approach to experimentation — comfortable proving something quickly before investing heavily in scaling it.
• A healthy interest in where AI is taking software engineering and how it can be used meaningfully rather than performatively.

Experience across Retail Media, AdTech, eCommerce, search, recommendations, ranking, real-time bidding or auction systems would obviously be incredibly relevant.
  
But it isn’t a prerequisite.
  
Epsilon is far more interested in the calibre of problems you’ve solved, the breadth of environments you’ve experienced and, importantly, how you think.
  
Why Epsilon?

Because senior technical careers shouldn’t have to end in people management.
  
This is a genuinely influential Principal IC position where you can remain deeply technical while having a meaningful say in architecture, product thinking and how engineering evolves across a sophisticated global technology business.
  
You’ll work alongside seriously capable engineers, Product and Data Science people who are comfortable challenging each other, exploring different ideas and changing direction when the evidence points somewhere better.
  
There’s scale here. Complexity. Technical depth. And enough freedom to actually influence how some very interesting problems get solved.
  
The role is Brisbane-based with a hybrid setup (Fortitude Valley), giving you the best of both worlds - proper face time with the people you’re solving these problems alongside, without needing to live in the office.
  
If you’ve reached the stage of your engineering career where you’re less interested in simply being handed another architecture problem and far more interested in understanding why it matters, what the right trade-off is and whether there might be a smarter way to solve it…
  
We should probably talk.
  
Hit APPLY, or come Fynd us here:
adam@fyndco.com.au