Data Migration Specialist at CoreWeave, London, 3 Months, £Contract Rate

What You’ll Do:

The Monolith AI Platform Engineering Team at CoreWeave is responsible for transitioning existing client environments to Monolith AI’s next-generation platform, maintaining the high velocity needed to support a rapidly growing customer base. This team works closely with Customer Success and Product to ensure migrations are accurate, meet defined business requirements, and are delivered at scale.

About the Role:

Monolith AI is seeking a talented Software Developer for an intensive 3-month migration project transitioning existing client environments to our next-generation platform. This role requires a developer who excels at rapidly understanding undocumented systems, extracting clarity from complex database structures, and building practical migration tooling in Python. You’ll work closely with our 15-person technical team (currently doubling), collaborating extensively with Customer Success and Product to ensure migrations meet defined business requirements while maintaining high velocity.

In this role, you will:

• Rapid System Understanding
  • Quickly grasp existing PostgreSQL database schemas through code inspection, team discussions, and reverse engineering
  • Understand new platform database architecture and how legacy data maps to the new structure
  • Work with pickle files and S3 object storage to understand serialized data structures
  • Extract clarity from poorly documented legacy systems through hands-on investigation
• Cross-Functional Requirements Gathering
  • Collaborate with Customer Success to understand client migration requirements and acceptance criteria
  • Partner with Product team to define and iterate on what constitutes acceptable migration outcomes
  • Balance technical constraints with business needs to establish pragmatic migration standards
  • Clarify ambiguous requirements and drive decisions on edge cases and trade-offs

• Product Context & Impact Analysis
  • Understand how database entries and S3-stored objects drive UI behavior and user workflows
  • Work with the existing team to learn system behavior through discussions and knowledge transfer
  • Identify how legacy data structures distribute across new platform tables and storage

• Migration Tool Development
  • Build Python migration scripts to convert legacy notebooks to the new platform format
  • Work with Flask and FastAPI layers to understand API interactions and data flow
  • Handle pickle file deserialization and data transformation logic
  • Implement validation against defined Customer Success requirements (not 100% data integrity)

• Velocity & Communication Management
  • Maintain rapid project pace with tight 3-month timeline
  • Provide frequent progress updates to the tech lead on development speed and blockers
  • Proactively communicate risks, timeline concerns, and decision points
  • Make pragmatic technical decisions that balance quality with delivery speed

• Testing & Validation Against Requirements
  • Test migration outputs against Customer Success acceptance criteria
  • Validate migrated notebooks meet defined business requirements
  • Identify and communicate gaps between migration output and requirements for product decisions

• Process Documentation & Knowledge Transfer
  • Document the migration process, key decisions, and data mapping logic
  • Create runbooks for executing migrations and handling common issues
  • Transfer knowledge primarily through discussions with the existing team
  • Prepare materials enabling team to execute and troubleshoot migrations post-contract

Who You Are:

• 3+ years of professional software development experience
• 2+ years working with Python in production environments
• Experience working with PostgreSQL databases and complex data structures
• Demonstrated ability to reverse engineer and understand undocumented systems
• Previous work in fast-paced, deadline-driven environments
• Programming: Strong Python proficiency including handling pickle files, data processing, and object serialization
• Databases: Solid understanding of PostgreSQL including complex data structures, relationships, and schema interpretation
• APIs: Familiarity with Flask and/or FastAPI frameworks and RESTful API concepts
• Cloud Storage: Experience with S3 or similar object storage services for reading/writing data
• System Investigation: Ability to read and understand existing codebases to extract system behavior
• Version Control: Proficiency with Git and collaborative development workflows

Preferred:

• Experience with data migration or system modernization projects
• Background working with legacy systems or technical debt remediation
• Familiarity with Jupyter notebooks or similar computational environments
• Previous contract or consulting roles requiring rapid onboarding
• Experience in startup or scale-up environments with evolving requirements
• Knowledge of data serialization formats and their trade-offs
• Prior work extracting understanding from poorly documented codebases
• Experience balancing technical perfection with business pragmatism