Data Migration Specialist in London

CoreWeave is The Essential Cloud for AI™. Built for pioneers by pioneers, CoreWeave delivers a platform of technology, tools, and teams that enables innovators to build and scale AI with confidence. Trusted by leading AI labs, startups, and global enterprises, CoreWeave combines superior infrastructure performance with deep technical expertise to accelerate breakthroughs and turn compute into capability.

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.

Why Monolith AI? At Monolith AI, we work hard, have fun, and move fast! We’re in an exciting stage of hyper-growth that you will not want to miss out on. We’re not afraid of a little chaos, and we’re constantly learning. Our team cares deeply about how we build our product and how we work together, which is represented through our core values:

• Be Curious at Your Core
• Act Like an Owner
• Empower Employees
• Deliver Best-in-Class Client Experiences
• Achieve More Together

We support and encourage an entrepreneurial outlook and independent thinking. We foster an environment that encourages collaboration and enables the development of innovative solutions to complex problems. As we get set for takeoff, the growth opportunities within the organisation are constantly expanding. You will be surrounded by some of the best talent in the industry, who will want to learn from you, too. Come join us!

To fulfil our obligation to protect client data, successful applicants offered employment with CoreWeave will be required to complete a basic criminal record check, conducted in compliance with GDPR. Employment offers are conditional upon receiving satisfactory check results.

What We Offer: In addition to a competitive salary, we offer a variety of benefits to support your needs, including:

• Family-level Medical Insurance
• Family-level Dental Insurance
• Generous Pension Contribution
• Life Assurance at 4x Salary
• Critical Illness Cover
• Employee Assistance Programme
• Tuition Reimbursement
• Work culture focused on innovative disruption

Benefits may vary by location.

Our Workplace: While we prioritize a hybrid work environment, remote work may be considered for candidates located more than 30 miles from an office, based on role requirements for specialized skill sets. New hires will be invited to attend onboarding at one of our hubs within their first month. Teams also gather quarterly to support collaboration.

CoreWeave is an equal opportunity employer, committed to fostering an inclusive and supportive workplace. All qualified applicants and candidates will receive consideration for employment without regard to race, color, religion, sex, disability, age, sexual orientation, gender identity, national origin, veteran status, or genetic information.

CoreWeave does not accept speculative CVs. Any unsolicited CVs received will be treated as the property of CoreWeave and your Terms & Conditions associated with the use of CVs will be considered null and void.

Export Control Compliance: This position requires access to export controlled information. To conform to U.S. Government export regulations applicable to that information, applicant must either be (A) a U.S. person, defined as a (i) U.S. citizen or national, (ii) U.S. lawful permanent resident (green card holder), (iii) refugee under 8 U.S.C. § 1157, or (iv) asylee under 8 U.S.C. § 1158, (B) eligible to access the export controlled information without a required export authorization, or (C) eligible and reasonably likely to obtain the required export authorization from the applicable U.S. government agency.