Principal AI Engineer
At a glance
Senior AI Engineering role at nexos.ai. Vilnius · full-time.
Pay not stated AI Engineer salary
aimlroles summary, based on the employer's posting.
What you'll do
- Set AI/ML direction by shaping research priorities, testing early concepts yourself and guiding architecture choices
- Explore frameworks and ideas such as retrieval, memory and agentic workflows, then take promising work into production
- Work with product managers and cross-functional teams from discovery through delivery, contributing as both engineer and technical guide
- Define and run evaluations for proprietary and open-source LLMs, weighing quality, cost and reliability
- Share practical AI expertise with colleagues and external audiences
What you bring
- You have led AI/ML work from initial planning through production and owned its results
- You can design and scale production AI systems, while still building and testing them hands-on
- You bring deep knowledge of LLMs, embeddings, multimodal systems, AI architectures and context engineering
- You have strong software engineering skills, including microservices, and have moved proofs of concept into production
Who this fits
This senior, hands-on role suits an experienced AI engineer who can set technical direction and still deliver production systems. The position is hybrid in Vilnius, Lithuania, with flexible working hours.
From the employer
Own the AI revolution. We're building an all-in-one AI platform to help teams do their best work and automate every routine task you can think of. We're looking for someone who operates at the highest technical level - equally at home prototyping a new idea on Monday and shaping our AI roadmap on Friday. If you want to do serious work and have real influence over where it goes, this is the role.
Main Responsibilities
Shape the AI/ML technical direction - contribute to research strategy, validate POCs hands-on, and bring the architectural perspective that influences how we build
Be the GenAI authority - stay ahead of the field, decide what's signal versus noise, and bring the team with you
Lead hands-on exploration of new concepts, frameworks, and tooling - context management, memory, retrieval, agentic loop, A2A and beyond - from experimentation all the way to production
Be a core part of product development - from discovery with PMs to delivery within cross-functional teams, operating as both a doer and a thought leader in the same sprint
Own the LLM evaluation framework (proprietary and OSS) - set the criteria, run the assessments, make the call on performance, cost, and reliability
Act as AI evangelist internally and externally - at this level, spreading serious AI thinking is part of the job, not a bonus
Core Requirements
Proven track record of driving AI/ML initiatives end-to-end in production - you've owned the outcome, not just the ticket
Expert ability to design, execute, and scale production-grade AI systems - and the hands-on instinct to still get in and build
Deep command of AI developer frameworks and tooling - with the judgment to make the right call, not just the popular one
Expert understanding of large language models, embeddings, multimodality, and AI architectures - including where they break
Advanced expertise in context engineering and deployed evaluations - you raise the bar for how the team thinks about this
Strong ownership and accountability - you can plan your own work, influence the team's direction, and still ship
A builder's instinct: moves fast when it matters, rigorous when it counts
Solid software engineering fundamentals, microservice architectures, and experience taking POCs through to production
Bonus Points For
Architect-level experience designing and shipping complex Agentic systems at scale
Deep expertise in data science methodologies, ML algorithms, and NLP - the fundamentals, not just the wrappers
Experience in backend engineering, API design, scalable systems, and Kubernetes
Track record of owning features end-to-end and working fluidly across engineering, product, sales, and marketing
Salary Ranges
Gross salary from 6600 EUR/Month (final compensation depends on exact experience)
What We Offer
Professional growth. Internal and external events, online training, conferences, books - everything you need to reach your full potential.
Health benefits. Private health insurance, online & on-site workouts (LT) / online workouts & sports access card (PL), consultations - to feel and be your best.
Team spirit. Team buildings and parties with games, shows, tastings, food coupons, gifts - and it's on us.
More free time. Stay with us and additional vacation days will be added to your calendar.
Additional paid leave. Additional days are covered by us in cases of illness or special occasions.
Flexibility. Flexible working time arrangement.