Applied Machine Learning Scientist/Engineer — LLMs

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At Sonder, we believe that every person deserves to feel safe, supported, and empowered to be at their best — wherever they are. Sonder's mobile platform provides 24/7, real-time support from a dedicated team of safety, medical, and mental health professionals, ensuring immediate care when needed. In critical situations, we offer on-the-ground assistance to manage time-sensitive incidents. By harnessing real-time insights, we enable organisations to take proactive steps toward a healthier, safer future with tangible bottom-line outcomes.

Are you a recent PhD graduate or Postdoctoral researcher passionate about applying cutting-edge AI to real-world problems? Join Sonder as an Applied Machine Learning Scientist/Engineer — focusing on LLM Research & Fine-Tuning Engineering, to build a new generation of AI systems that directly impact human well-being and safety. This role is distinct from typical AI tooling or RAG-based roles.

We are not seeking candidates whose primary experience is in building vector search systems or integrating off-the-shelf APIs. We require deep, hands-on expertise with the internal workings of large language models. Your work will be instrumental in developing our personalisation engine and fine-tuning state-of-the-art open-source LLMs like LLaMa, Mistral, and DeepSeek. Your research will translate into specialised LLMs that provide empathetic, life-saving support to our members.

• Research, fine-tune, and optimise open-source LLMs using techniques such as PEFT, LoRA, and QLoRA to build proprietary AI models.
• Design and implement personalisation and recommendation engines to deliver tailored, proactive support.
• Develop and maintain robust machine learning pipelines for model training, evaluation, and deployment.
• Collaborate with cross-functional teams (product managers, software engineers, mental health professionals) to translate research into product features.
• Stay current with AI and LLM advancements; apply new techniques to improve systems.
• Publish and/or present research findings at conferences or in journals where appropriate.

• Recently completed PhD or Postdoctoral experience in Machine Learning, AI, Computer Science, or related field.
• Deep understanding of Transformer architectures, attention mechanisms, and training dynamics.
• Hands-on experience fine-tuning open-source LLMs (e.g., LLaMa, Mistral, DeepSeek).
• Strong CS fundamentals and Python proficiency.
• Experience with deep learning frameworks such as PyTorch or TensorFlow.
• Passion for applying AI to high-impact domains such as mental health and well-being.

Candidates with primary experience limited to RAG systems or MLOps tooling are not a fit for this role.

• Experience with distributed training for large models.
• Familiarity with cloud-based ML stacks (e.g., AWS, GCP).
• Track record of peer-reviewed publications in AI/ML conferences.

Your work will directly contribute to saving lives and improving mental well-being on a global scale. You will shape our core AI technology from the ground up and grow as a leader in a mission-driven environment. You'll have freedom to explore new ideas and resources to deploy them, making a tangible difference.

• Hybrid and flexible working environment for balance of in-office collaboration and remote work.
• Free access to the Sonder app for you and your family for 24/7 support.
• Development budget and study leave; parental leave with return-to-work policy.
• Employee Share Option Plan (ESOP) and salary packaging options.
• Wellbeing stipend and annual allocations for wellbeing activities.
• Coffee, catered lunches, team social funds, and dog-friendly office.
• Volunteer leave: 2 days per year for community involvement.

We are committed to a diverse and inclusive workplace. If you need support with your application, please reach out. Due to the nature of our industry, all employees are required to complete a National Police Check and Working With Children Check.

Sonder is for Everyone. We encourage applications from people of all backgrounds, experiences, abilities, and identities.