Bain · Technology / E-Commerce · Advanced · 35-45 min

Migrate monolithic e-commerce platform to microservices

Migrate monolithic e-commerce platform to microservices is an advanced Bain technology / e-commerce case interview that runs 35-45 min. Design a pragmatic migration strategy that balances technical modernization with business continuity, define success metrics. A strong answer works through 5 phases: Service decomposition strategy; Data architecture and migration; Migration sequencing by business priority; DevOps and infrastructure investments; Team structure and skill requirements.

Last updated 2026-09-05

The brief

A $5B e-commerce company’s monolithic platform is limiting feature velocity and scalability. Built 10 years ago, it serves 50M monthly users across 5 geographies. Architect a migration to microservices that improves agility and reliability without disrupting the business.

How to approach it

  1. Service decomposition strategy
  2. Data architecture and migration
  3. Migration sequencing by business priority
  4. DevOps and infrastructure investments
  5. Team structure and skill requirements

What a strong answer does

  • Design a pragmatic migration strategy that balances technical modernization with business continuity, define success metrics.
  • Strangler pattern migration over 3 years, starting with high-value, loosely-coupled services (recommendations, search). Maintain monolith for stable, complex services (checkout, inventory). Establish DevOps and observability tooling.

Practice drills

  • Identify candidate services for strangler pattern migration.
  • Design data migration strategy for a service (e.g., product catalog).
  • Map team structure and ownership model for microservices.
  • Estimate total TCO and effort for 3-year migration.

Why this case

Tests architecture thinking, risk management, and ability to execute large-scale technical transformations without business disruption.

Adapted from Bain Platform Architecture case (official sample).

Cases are written in each firm's style, written and reviewed by working consultants; they are not the firms' own published cases.

More Bain cases