Product Engineer (UI / Frontend)

About the role

Maincode is building the next version of Matilda, the first large language model built and trained from scratch in Australia. We are now scaling the model and deploying it as a live production system.

To do that, we build AI systems from first principles. We design the architectures, run the infrastructure, shape the training process, and operate the systems that serve our models.

Matilda is a production system, not a research prototype, built to be deployed and served for open public access. If the training stack is how Matilda learns, the product is how people experience it. This role sits directly in that layer.

You will help build the user-facing experience of Matilda. Not just how it is implemented, but how it feels, behaves, and communicates with users. You will contribute to designing and building the interfaces that turn a model into a coherent product.

This is not a pure handoff role. You will work closely on both the UX and the implementation, shaping interactions and details directly in code.

What you would actually do

You will contribute to the product surface of Matilda’s public interface and internal tools. This includes:

• Building the core web interface for interacting with Matilda (chat, sessions, history, settings)

• Implementing fast, reliable streaming UX for model outputs (real-time tokens, partial responses, cancellation, retries)

• Contributing to interaction design across common and edge-case flows (latency, uncertainty, refusals, errors)

• Helping design UI workflows that support safe and responsible use (reporting, feedback, content handling)

• Iterating on layout, typography, spacing, and interaction details directly in code

• Improving perceived performance and responsiveness through thoughtful UI decisions

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• Building internal tools and dashboards with a strong focus on clarity and usability

• Working closely with backend and infra engineers to integrate APIs, auth, and system constraints

You will spend time in code, but also thinking about flows, edge cases, and how the product behaves for real users.

The kind of person who does well here

We are looking for engineers early in their careers who care deeply about how products feel to use, not just whether they work. You may have one or two years of experience building production software.

People who tend to do well here:

• Have strong visual taste and attention to detail (spacing, typography, motion, polish)

• Care about interaction quality and the small details that shape user experience

• Enjoy working across design and engineering rather than staying strictly in one lane

• Think in terms of user flows and states, not just components

• Are comfortable making reasonable UX decisions and iterating quickly

• Have solid engineering fundamentals and write clean, maintainable code

• Are curious, practical, and willing to learn from real usage

You do not need formal design training, but you should have a clear sense of what good looks like.

How you would work

You will work across design and engineering in a tight loop. You should be comfortable:

• Working in TypeScript and modern front end tooling

• Building production web applications (component architecture, state management, API integration)

• Implementing real-time or streaming interfaces (for example, via SSE or WebSockets)

• Iterating on UI directly in code

• Using modern tooling, including coding agents, to move quickly and explore ideas

• Debugging issues that emerge under real conditions

• Collaborating closely with research, backend, and infrastructure teams

Much of the work sits between product, UX, and the underlying model. The model evolves quickly, but the experience must remain clear and reliable.

Why Maincode

Maincode builds AI systems end to end. We prepare the data, design the training process, run the infrastructure, and operate the models ourselves. You will work with a small team that:

• Builds the full AI stack rather than outsourcing it

• Treats product experience as part of the intelligence system itself

• Values taste, creative judgment, and craft

• Is building long-term capability in training, deploying, and operating large models

If you care about building thoughtful, high-quality user experiences and want to work close to the core system, you will be well placed here.

What to include in your application

We care a lot about what you have actually built.

Please include examples of products, interfaces, or features you have worked on that you are proud of. This can be professional work or personal projects. We are particularly interested in:

• Interfaces where you shaped the UX, not just implemented it

• Work that shows attention to detail and visual craft

• Anything that demonstrates good judgment in interaction or product decisions

Note

This is a full time role based in Melbourne, working closely with our in person engineering and research team. At this time we are not able to offer visa sponsorship, so applicants must have existing and unrestricted work rights in Australia.