AI Researcher (Post-Training)

• At Sonar, we are seeking an ambitious senior researcher to join our cross-disciplinary team, innovating and developing the next generation of solutions to build enterprise-grade coding agents and models. You will harness Sonar’s deep experience in static analysis, and combine it with your experience and leading techniques in large language model post-training
• If you are interested in being hands-on with state-of-the-art research, building practical solutions that deliver high-impact for customers, and working within a team of innovative researchers and engineers, this role is for you
• Outcome Driven Development: Work in a team developing and implementing advanced products that enable customers to post-train models to power their agentic coding practices. These agents need to generate high-quality code that meets their enterprise standards and software development best practices
• Translate Prototypes to Products: Collaborate closely with researchers, research engineers, MLOps and engineers within the team to design hypotheses and experiments, iterate proofs-of-concept quickly and develop successful prototypes into cutting-edge products
• Subject Matter Expert: You will contribute and discuss ideas within our cross-disciplinary team, driving towards the next generation of coding model post-training for enterprises
• Spearhead Research & Innovation: Stay up-to-date with the latest LLM and agentic developments; you are driven by learning and teaching others. You will need to explain complex technical details and concepts to both technical and non-technical audiences

Benefits

• 401K Plan: Sonar US matches up to 4% of gross salary
• 90% healthcare premium coverage for employees, 60% for dependents
• EAP (Employee Assistance Program) Health Savings Accounts (HSA, FSA, DCFSA). Supplemental coverage is offered by EE’s expense
• Life and disability insurances fully paid by Sonar. Sonar covers 100% of Telemedicine for FTE whom are covered by Sonar medical
• Hospital Indemnity, Accident, Critical Illness
• Pet Insurance
• Time Off: 25 PTO days plus additional days based on seniority and circumstances
• Commuting: Public transport reimbursement of 60% for annual subscription
• Free parking space
• Pension: Sonar UK contributes 50% of the total costs, which amounts to 5% of your gross salary for saving. Employees contribute the other 5%
• Flexibility to work from home 2 days a week on Wednesdays and Fridays
• Time Off: 28 PTO days, plus additional days based on seniority and circumstances
• Health Insurance: Sonar covers 100% of the employee premiums for medical, dental, and EAP (Employee Assistance Program) plans through BUPA
• Commuting: we will reimburse 60% towards the cost of an annual public transport pass- Fluency with Python including core ML frameworks, experience with Rust or any of SonarQube’s flagship languages (C#, C++, JS/TS, Java) is a plus
• Data-centric AI methods, including synthetic data and curation
• Excellent communication skills in English and a talent for explaining complex scientific topics clearly and concisely
• Verifier-based RL frameworks (RLVR)
• Parameter-efficient fine-tuning (PEFT)
• Preference and Safety Alignment
• Expertise in post-training of large language models, including:
• Policy optimization algorithms (e.g. GRPO, PPO)
• Supervised fine-tuning (SFT)
• An advanced academic background (Master’s or PhD) in Computer Science, Machine Learning, or a related quantitative field
• Experience of driving research projects, delivering valuable findings and prototypes, and then converting them into products
• 4+ years industry experience in machine learning, with a solid understanding of modern software engineering practices and tools