John Ojo

Platform Migration · Technical Lead · Oct 2025 – Present

• Led full-stack migration of a benefits platform (4M+ records, ~200 TPS peak, P99 latency under 55 ms, 100K+ users) from a monolithic shared pipeline into a standalone React application with independent releases.
• Reduced the release cycle from 4–5 days to 1–2 days and rollback time from hours to under 30 minutes.
• Built an aggregated API consolidating 4 microservices into a single response, eliminating an N+1 call pattern (8+ round-trips to 1) and reducing frontend latency by over 75%.
• Designed a dual-auth reverse proxy (SigV4 + token-based) with API Gateway, replacing an intermediary service layer for all GraphQL/REST operations.
• Built an automated data validation pipeline (S3, SQS, Lambda) comparing legacy and new endpoints field by field across 4M+ records to guarantee zero data loss during cutover.
• Implemented a phased rollout with independent feature flags and wave-based targeting (45 to 100K+ users), with full observability via custom telemetry, CloudWatch dashboards and Athena queries.
• Created a Cypress E2E suite (80 automated tests, 134-case QA plan) and authored onboarding documentation adopted as the team standard for new engineers.

Service Modernization · Jul 2023 – Oct 2025

• Migrated a high-throughput benefits service (4M+ DynamoDB records) to ECS Fargate (CDK), reducing support tickets 5%+ year on year and eliminating OS patching overhead.
• Resolved a production-blocking 403 auth failure by tracing it to API Gateway dropping SigV4 headers, and redesigned the networking (NLB to ALB) as a permanent fix.
• Built a serverless CMS (Lambda, Step Functions, DynamoDB) that reduced engineering dependency for content updates by 80% and time-to-market from days to hours, saving 3 developer-months a year.
• Developed a geospatial clinic search API (AWS Location Service) with a cache-on-first-visit strategy on Fargate, helping employees across 10+ clinic locations find the nearest care in under 2 seconds.
• Built local development stack infrastructure (CDK, Docker) that cut the test cycle from 1.5 hours to 10 minutes for 8 engineers, and led its adoption across the team.
• Pioneered chaos engineering with AWS Fault Injection Simulator, organised and led live gameday exercises, and authored adoption documentation now used org-wide.
• Migrated containers to ARM64/Graviton for ~20% compute cost reduction and implemented CI/CD with alarm-triggered automated rollback.

Second internship · Service migration · May – Aug 2022

• Migrated a legacy service onto native AWS, using Lambda with API Gateway as the compute platform.
• Created and delegated the service's DNS hosted zone.
• Ran end-to-end testing before onboarding internal and external clients.

First internship · FAQ chatbot · Jun – Aug 2021

• Built a chatbot with Amazon Lex and QnABot that answered common customer questions automatically, reducing the load on the people answering them.
• Built the chat interface with the Lex Web UI and Angular so users could talk to the bot.