John William Lim

Senior Software Engineer

Deloitte

Mar 2023 - Current (3 years 8 months)

Designed and built scalable backend services in Go and Python for marketplace and digital commerce clients,
delivering APIs and internal service integrations for catalog, order, seller, and fulfillment workflows.
Implemented gRPC and REST services backed by PostgreSQL and Redis to support high-throughput
transactional flows, reducing average service latency by 18% through query tuning, caching, and more efficient
request handling.
Integrated third-party partner APIs for payments, logistics, and seller operations, improving platform reliability and
reducing manual operational handoffs across client business teams.
Owned production monitoring and operational readiness for backend services by adding alerting,

Full Stack Developer

KITRUM

Jul 2021 - Feb 2023 (1 year 8 months)

Built backend services for commerce and marketplace products using Go, Python, PostgreSQL, Redis, and
RabbitMQ, supporting order management, inventory, checkout, shipment, and seller-facing workflows.
Developed and maintained core APIs for customer and merchant experiences, enabling smoother integration
between internal services and external systems used by payment, shipping, and catalog partners.
Increased peak-hour request throughput by about 22% by restructuring asynchronous processing, optimizing
database access patterns, and moving time-sensitive tasks off synchronous request paths.
Lowered API response times by about 17% through PostgreSQL query tuning, Redis caching, and improved
pagination strategi

Backend Developer

NCS

Sep 2019 - Dec 2020 (1 year 4 months)

Built backend services for document ingestion, OCR, metadata extraction, and compliance workflows.
Designed asynchronous pipelines using Kafka, Celery, and Redis for large-scale document processing.
Built secure APIs and Elasticsearch search services for multi-tenant document workflows.
Challenges and Solutions: Handling large document volumes while maintaining processing speed and reliable search. Solved this
with async pipelines, OCR automation, and optimized indexing and retrieval services.

Junior Software Developer

Shopee

Dec 2017 - Sep 2019 (1 year 10 months)

Built backend services and APIs for Al-powered features and internal automation tools.
Improved preprocessing, validation, and error handling for more reliable production workflows.
Challenges and Solutions: Improving the stability of Al-enabled backend workflows in production. Solved this through stronger
preprocessing, validation, and monitoring practices.

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John William Lim

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