Software Developer - Python - Data Migration

We're supporting a fast-growing AI scale-up on an intensive 3-month migration programme, moving existing client environments onto a next-generation platform. This is a hands-on role for a pragmatic Python developer who enjoys untangling Legacy systems, working at pace, and delivering outcomes rather than perfection., You'll join a rapidly scaling engineering team to design and build migration tooling that transitions complex, poorly documented client environments into a modern platform. The work is investigative, collaborative, and delivery-focused, requiring close alignment with Product and Customer Success to define and validate what "good" looks like., * Rapidly reverse-engineer undocumented PostgreSQL schemas and Legacy data structures

• Understand how existing database records and S3-stored objects drive product behaviour
• Build Python-based migration scripts to transform Legacy notebooks and data into new platform formats
• Handle pickle file deserialisation and complex data transformation logic
• Collaborate with Product and Customer Success to define migration acceptance criteria
• Balance speed and quality to meet an aggressive delivery timeline
• Validate migration outputs against agreed business requirements
• Document migration logic, decisions, and create runbooks for handover

• Strong Python development experience in production environments
• Solid PostgreSQL knowledge, including complex schemas and relationships
• Proven ability to reverse-engineer undocumented or Legacy systems
• Experience working with APIs (Flask and/or FastAPI)
• Familiarity with S3 or similar object storage
• Confident communicator able to explain technical concepts to non-technical stakeholders
• Comfortable working at pace with ambiguity and evolving requirements

Desirable

• Experience delivering data migration or platform modernisation projects
• Exposure to Jupyter notebooks or computational notebook environments
• Background in consulting, contracting, or startup environments
• Experience working with Legacy systems and technical debt
• Knowledge of data serialisation formats and trade-offs