LLM Engineer

Ultralytics; Madrid; Hybrid; EUR 142,000 - 189,000; Full time

Benefits offered by this job

Equity

Hybrid schedule

24 days vacation

Birthday off

Apple gear

Job summary

Ultralytics in London is seeking an experienced LLM Engineer to lead development of AI-powered language model capabilities within our YOLO ecosystem.

You will work on multi-API workflows, RAG systems, and data pipelines, collaborating with the YOLO team to deliver multimodal solutions.

Hybrid work (3 days in-office, 2 remote) with equity, 24 days vacation, and cutting-edge tools. We value fast-paced problem solving and open collaboration.

Qualifications

• 5+ years of software engineering with AI/ML focus required.
• Expert-level Python and PyTorch proficiency.
• Experience building and deploying apps with LLM APIs (OpenAI, Anthropic, Gemini, DeepSeek).
• Hands-on with full RAG pipelines: embeddings, rerankers, vector indexing (MongoDB).
• LLM fine-tuning, prompt engineering, performance optimization.
• MLOps awareness and CI/CD with GitHub Actions.
• Interest in computer vision and YOLO models.

Responsibilities

• Develop and scale LLM-powered applications via multiple APIs.
• Implement multi-API workflows with LiteLLM.
• Build RAG systems with embeddings, rerankers, and query enrichment.
• Design data pipelines and vector storage (MongoDB Atlas Vector Search).
• Fine-tune LLMs on custom datasets for docs and support.
• Collaborate with YOLO team on multimodal solutions.
• Automate deployment and testing with CI/CD (GitHub Actions).

Skills

5+ yrs AI experience

Python

PyTorch

LLM APIs

Tools

OpenAI API

Anthropic API

Gemini API

LiteLLM

MongoDB

GitHub Actions

Job description

About Ultralytics

At Ultralytics, we commit to relentless innovation in the AI space and seek team members who resonate with our ambition to produce the world's best YOLO AI models. If you're obsessed with AI, eager to make an impact on the world, and thrive in dynamic, high-intensity environments, we invite you to apply for a position on our team.

Where and how you can work

This full-time LLM Engineer position is based at our brand-new Ultralytics office in London, UK, with a hybrid model of three days in-office and two days remote. Applicants must have legal authorization to work in the UK, as Ultralytics does not provide visa sponsorship.

What you'll do

As an LLM Engineer at Ultralytics, you will spearhead the development and integration of advanced language model capabilities across our ecosystem. You will work on cutting-edge projects that merge the power of large language models (LLMs) with our state-of-the-art computer vision technologies. Key responsibilities include:

• Developing and scaling robust LLM-powered applications using a variety of APIs, including OpenAI, Anthropic, and Gemini.

• Implementing and managing multi-API workflows using tools like LiteLLM to ensure flexibility and resilience.

• Building sophisticated Retrieval-Augmented Generation (RAG) systems, leveraging advanced techniques like embeddings with Voyage AI, rerankers, and query enrichment.

• Designing and maintaining efficient data pipelines and vector storage solutions using MongoDB Atlas Vector Search.

• Fine-tuning LLMs on custom datasets to enhance performance for specialized tasks related to our documentation and user support.

• Collaborating with our YOLO development team to explore and build innovative multimodal solutions.

• Automating deployment and testing processes using CI/CD pipelines with GitHub Actions.

Your work will directly enhance the Ultralytics Platform and empower our global community of developers and researchers.

Skills and experience

• 5+ years of experience in software engineering, with a strong focus on AI and machine learning (ML).

• Expert-level proficiency in Python and deep learning frameworks, particularly PyTorch.

• Proven experience building and deploying applications with LLM APIs such as OpenAI, Anthropic, Gemini, and DeepSeek.

• Hands-on experience with the full RAG pipeline, including vector embeddings, rerankers, and data indexing in databases like MongoDB.

• Practical knowledge of LLM fine-tuning, prompt engineering, and performance optimization.

• Familiarity with MLOps principles and tools, including CI/CD with GitHub Actions.

• A strong interest in computer vision and an understanding of object detection models like Ultralytics YOLO26 is a significant plus.

• Excellent problem-solving skills and the ability to perform in a fast-paced, high-intensity environment.

Cultural fit

Ultralytics is a high-performance environment for world-class talent obsessed with achieving extraordinary results. We operate at a relentless pace, demanding exceptional dedication and an unwavering commitment to excellence, guided by our mission, vision, and values. Our team thrives on audacious goals and absolute ownership. This is not a conventional workplace. If your priority is predictable comfort or a standard work-life balance over the relentless pursuit of progress, Ultralytics is not for you. We seek driven individuals prepared for the profound personal investment required to make a defining contribution to the future of AI.

Compensation and benefits

• Competitive salary: Highly competitive based on experience.
• Equity packages: Participate directly in our company's growth and success.
• Hybrid flexibility: 3 days per week in our brand-new office — 2 days remote.
• Generous time off: 24 days vacation, your birthday off, plus local holidays.
• Flexible working hours: Tailor your working hours to suit your productivity.
• Tech & tools: Engage with cutting-edge AI projects and contribute to leading open-source software.
• Gear: Brand-new Apple MacBook Air/Pro, Apple Studio Display, and AirPods Pro 3.
• Team: Become part of a supportive and passionate team environment.

What we offer

Cutting-Edge, Next-Generation AI Computer Vision Technology: Contribute to building cutting-edge computer vision AI models based on the YOLO framework.

Impactful Work: Shape the future of AI-powered solutions that transform industries.

Collaborative Culture: Join a talented and passionate team that values open communication and innovation.

Ultralytics Handbook

Comprehensive guide to our company's mission, vision, values, and operational practices. This handbook is designed to provide key insights and resources for our (future) team members, collaborators, and community to align with Ultralytics' core principles.

Link: https://handbook.ultralytics.com/

Ultralytics is an equal opportunity employer committed to building an inclusive workplace. We believe that everyone should be able to bring their whole selves to work, and we do not discriminate on the basis of race, religion, national origin, gender, sexual orientation, age, veteran status, disability, or any other legally protected status.