Software Engineer

Meta – Software Engineer II (IC3) / Software Engineer III (IC4)

Location: London, UK

Working Model: Hybrid – 3 days onsite

Contract: 6 months, extension possible

Hours: 40 hours/week

About the Opportunity

We are looking for Research Engineers to join Meta’s Fundamental AI Research (FAIR) team, working on cutting-edge AI and machine learning research.

The team is focused on making fundamental advances in AI, including Large Language Models (LLMs), AI agents, generative AI, reinforcement learning, synthetic data and multi-agent systems.

This is a highly hands-on engineering role where you will work closely with researchers and engineers to turn research ideas into working systems and conduct complex experiments at scale.

Key Responsibilities

• Build and improve machine learning and AI systems at scale.
• Develop research tooling and infrastructure to support AI/ML experimentation.
• Design and execute complex experiments involving large AI models and datasets.
• Work with LLMs, AI agents and generative AI technologies.
• Explore areas such as LLM post-training, reinforcement learning and synthetic data.
• Write high-quality, production-level Python code.
• Use PyTorch and other ML frameworks to develop and evaluate models.
• Collaborate closely with research scientists and engineers.
• Translate research insights into practical engineering solutions.
• Work in a fast-paced environment where strong execution and problem-solving are essential.

Required Experience

• Strong experience in Machine Learning / Artificial Intelligence / Deep Learning.
• Strong Python programming skills.
• Hands-on experience with PyTorch.
• Experience working with large datasets and ML models at scale.
• Experience designing and running complex ML/AI experiments.
• Strong software engineering and problem-solving ability.
• Experience with LLMs, Generative AI, AI Agents or Foundation Models is highly relevant.
• Exposure to LLM post-training, reinforcement learning or synthetic data is advantageous.
• A strong scientific/research mindset and ability to work collaboratively.

Level 1 — Software Engineer II (IC3)

Best suited to candidates with solid hands-on ML/AI engineering experience who can independently contribute to research projects and experimentation.

Level 2 — Software Engineer III (IC4)

Best suited to more experienced ML/AI engineers who can take greater ownership of complex research and engineering problems and contribute at a higher technical level.

Please note: The core technical requirements and project are the same for both levels; the primary distinction is the candidate's depth of experience, technical ownership and seniority.