Senior AI Engineer, Models

You own how good our models are. In the near term that means making our agents indistinguishable from a human in conversation, by working the prompt and the harness together. After that it means bringing the weights in-house: fine-tuning an open-weights model, serving it in production, and running it well enough that we stop depending on any single provider.

This role is fully remote and based in Lithuania. We have no office, so remote here is genuine rather than a policy. We are not able to hire outside Lithuania for this role and do not provide visa sponsorship.

About CUBE AI

CUBE AI is an Agentic Crime Prevention Platform, built at the intersection of agentic AI, cybersecurity, and fraud prevention. We serve the institutions on the front line of an exploding wave of AI-powered crime: banks, fintechs, and the platforms criminals cannot operate without. Our mission is ambitious: make the world a safer place. How we do it is the part we're most excited about, and the part we're happy to walk you through in a conversation rather than on the open internet.

Why this is the seat to take

This is a rare seat on a rocket ship. CUBE AI is early, exceptionally ambitious, and backed by some of the world's leading investors. Our founders have built and scaled startups to unicorn valuations and exits, and have run mega teams at mega companies. We are building the company that puts the institutions the modern economy runs on back on offense against AI-powered crime. The closest analogy is joining Palantir in its early days: a hard mission, a category we're defining rather than entering, and a small group of exceptional people compounding fast. If you want a comfortable role, this isn't it. If you want the defining chapter of your career, your best work alongside people who make you sharper, keep reading.

What you'll do

• Own model quality, and be accountable for how convincing our agents are.
• Fine-tune, serve and operate an open-weights model in production, including the serving infrastructure.
• Remove our dependence on any single model provider.
• Bring inference cost down without giving up quality.
• Build the evaluation infrastructure that turns model quality into a number rather than an opinion.
• Own the decision about which model runs where, and revisit it as the frontier moves.
• Partner with our agent capabilities engineer, who comes at the same target from the harness side.

Our stack

• Python, LangChain and LangGraph
• Frontier LLM APIs today, through the OpenAI SDK
• Pydantic for structured output, PostgreSQL for state
• GKE, Docker and GitHub Actions
• Open-weights fine-tuning and serving does not exist here yet. Building it is the role.
• AI-assisted, agentic development workflows

What we're looking for

The bar (non-negotiable, every role):

• Extreme drive and passion for the work and the mission.
• Extreme ability to learn fast and operate with confidence in uncertainty.
• Extreme IQ and EQ. You raise the level of every room, and you lose an argument gracefully the moment someone's right.

For this role specifically:

• You have taken LLM systems to production and improved them there.
• You have fine-tuned an open-weights model and served it to real traffic, and can say what broke.
• Working knowledge of serving stacks such as vLLM or TGI, and what they cost to run.
• Evaluation discipline, including building the harness rather than eyeballing outputs.
• GPU-aware: quantisation, batching, and throughput against latency.
• Fluent written and spoken English.

Bonus points

• Preference optimisation such as DPO or RLHF, or distillation.
• Adversarial robustness, red-teaming or model evaluation research.
• Cost modelling for inference at scale.
• An adversarial domain: fraud, security or abuse.

How we work and who thrives here

We write more than we meet and move at warp speed. We're an AI-first company: every person here is amplified by a layer of AI agents, and we scale capability, not headcount. We don't buy services, we buy results. We're drivers, not passengers, so we hire people who go and do it without waiting for permission. We move fast, and we use judgment where it counts: we hold sensitive data and the trust of the institutions we protect, and we never cut corners there. Our culture runs on five virtues:

• A pedantic bar for quality. Work that is thorough, complete, and on time. We trust each other to deliver, fully.
• Radical ownership. See it, own it, fix it. Never defer a problem or an opportunity. You will never be reprimanded for taking initiative.
• Relentless energy and audacity. Building something exceptional demands enormous energy. We move forward with maximum drive.
• Automate everything. We scale the capability of our people, not the headcount. We always hunt the 10x multiplier, working alongside AI agents rather than piling on process.
• Have fun. We work with people we genuinely enjoy. It gets us through the hard stretches and keeps politics out.

What's in it for you

• Uncapped growth. In a company moving this fast, scope finds the people who can carry it. Ownership and title are earned in months, not years.
• Real self-realization. This is a place to become the most capable version of yourself, next to people operating at the top of their game.
• You share in the outcome. When the company wins big, you win big.

What we offer

Join a rocket ship. Let's discuss compensation and the rest of the details on our call.

CUBE AI is an equal-opportunity employer. We welcome applicants of every background and will support any accommodations you need during the hiring process.