• Built a checkout processing service in Ruby with controlled concurrency, allowing faster parallel transactions & cutting payment delays during peak hours by 35%. Also reduced database deadlock issues.

• Created a frontend customization system using React + TypeScript. Shifted Shopify's storefront editor to a dynamic model, which helped cut UI error reports by 25%.

• Improved GraphQL API speed by batching resolver calls & removing repeated field evaluations - boosted response time by 40% & made the merchant dashboard quicker.

• Made PostgreSQL queries faster for sales analytics by using indexed materialized views & preloading commonly used data. Dropped report load time from minutes down to seconds.

• Set up a CI/CD pipeline with Jenkins + AWS. Changed how artifacts & DB migrations are deployed, making rollouts more reliable & cutting rollback cases by 30%.

• Built a distributed webhook system using Ruby on Rails, PostgreSQL & AWS SQS to support async event handling, letting millions of 3rd-party integrations receive webhooks without delay.

• Created an API request queue with Redis caching & backpressure control to keep response times stable during large spikes in repo activity.

• Improved PostgreSQL queries & indexing for GitHub's internal repo metadata, cutting execution time by 50% & speeding up repo search & navigation.

• Tuned Sidekiq worker allocation across AWS regions to scale background jobs better, cutting task delays for events like issue tracking & repo updates.

• Made repo permission checks faster by using recursive queries & connection pooling in PostgreSQL, bringing down response times by 35% on big enterprise accounts.

• Reworked GitHub’s GraphQL API to support deferred execution, reducing heavy-query load on the primary DB without affecting data accuracy.

• Built auto-rollback support into Jenkins-based CI/CD pipelines, allowing quick fault detection & fast rollback of failed API deployments.

• Built policy transaction handlers in Aflac's monolithic Rails app, moving from direct DB writes to async job-based updates. This cut batch update time by 40% during peak policy renewals.

• Swapped out flaky cron jobs with Sidekiq-based async jobs, using structured retries & a dead-letter queue for better handling of mass policy updates.

• Replaced older SOAP services with REST APIs, introducing consistent data formats to fix mismatches across internal calls.

• Set up a Jenkins-based deployment flow with staged rollouts & auto rollback checks to reduce production issues from manual steps.