Posted 2 days ago
Senior Fullstack Engineer (Backend leaning, AI-Facing Systems) - $180K - $200K + super + equity | Sydney-based hybrid | AI-first infrastructure
This is one of those rare engineering roles that actually lives up to the hype. Join and immediately contribute to a high-calibre founding team building real, production-grade AI systems. Their product is already in the hands of paying customers, and demand is outpacing bandwidth. They need someone exceptional to help them scale.
You'll design and ship backend architecture that powers intelligent agents used by government agencies, global enterprises, and mid-size tech firms. These systems automate complex business processes like RFPs, audits, and compliance through deep integration with CRMs, ERPs, and LLMs.
Why this role matters
This isn't basic software, it's orchestrating distributed systems around foundation models and vector databases, with serious uptime and performance requirements. You'll be one of the first five engineers on the team, shaping architecture, tooling, and technical direction.
There's AI in the stack, but it's the hard part of AI. You'll work with model scaffolding, low-latency services, embedding search, and finetuning pipelines. You don't need to have done it all before, but you should be deeply curious and ready to learn fast.
You'll thrive here if you
Have strong experience in backend-heavy roles using Node.js and TypeScript
Have worked on distributed systems, real-time APIs, or performance-critical infrastructure
Have meaningful experience with AI projects, such as finetuning models, using Langchain, or working with vector databases like pgvector, Pinecone, or Neo4j
Have shipped serious features end-to-end in a startup or fast-paced team
Want to help build not just code, but a company
Bonus points if you've worked on knowledge graphs, LLM integration, or embedding pipelines.
What's in it for you
Massive impact. You'll be building the product, not maintaining it
Serious technical stretch. This is complex, greenfield work
Equity upside. Early-stage stock options are available
Founder access. Collaborate directly with a hands-on, technical founder
Speed and autonomy. Work with a sharp, lean team that values deep work
Interested? Apply now or message Sean on /
About The Onset
Sydney, NSW, Australia
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