OneCompiler

Tell me a time when you had to solve difficult problem

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1. Tell me a time when you had to solve difficult problem

Situation:

  • At Reputation.com, legacy Integrator Service was handling external API syncs.
  • It was monolithic, fragile, and hard to scale.
  • Business decided to migrate 200+ customers to a new Rep Connector microservice built on modern stack.
  • Risk: API failures, data loss, downtime during cutover.

Task:

  • Lead the migration from old service to Rep Connector.
  • Ensure data consistency across millions of API syncs.
  • Minimize downtime and errors for live customers.

Action:

Designed migration plan:

  • Used Kafka + retry queues for reliable event processing.
  • Added idempotency keys to prevent duplicate API calls.
  • Implemented feature flags to switch customers gradually.

Validation strategy:

  • Built scripts to compare legacy vs new system outputs.
  • Added monitoring dashboards in ELK + Grafana for API failures.

Risk mitigation:

  • Created rollback path → route traffic back to old integrator if issues.
  • Conducted pilot migration with 5 customers first.

Execution:

  • Migrated in controlled batches (20–30 customers at a time).
  • Daily sync validations with QA before expanding further.
  • On-call monitoring during final cutover.

Result

  • Successfully migrated 200+ customers with zero downtime.
  • Improved throughput by 30–40% due to microservice architecture.
  • Reduced API failures significantly with retries + idempotency.
  • Leadership recognized it as a model migration strategy.
  • Built a reusable framework for future customer migrations.