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michael weru

@michaelweru

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I’m a Senior Software Engineer building AI-driven payments with Node.js, Java, and React.

United States

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What I'm looking for

I’m looking for a role where I can build secure, high-performance payment and platform services, partner with product, and apply AI (RAG, fraud, support automation) to ship measurable customer impact at scale.

I’m a Senior Software Engineer with 13+ years building fintech, e-commerce, and retail systems—delivering payment APIs, distributed transaction processing, and merchant workflows across Stripe, Shopify, Walmart, and Affirm. I build for performance and reliability, including OAuth 2.0/JWT authentication, caching, and event-driven architectures that achieve sub-200ms response targets.

I also apply AI to real production problems: Python-based fraud detection, recommendation engines, and customer support automation using Azure OpenAI and RAG pipelines. From PCI DSS-aligned payment handling to headless UI migrations and Kafka-powered global tax workflows across 30+ countries, I focus on secure integrations, measurable latency improvements, and systems that scale under peak demand.

Experience

Work history, roles, and key accomplishments

Current

Senior Software Engineer

Current

Work & Co

Oct 2023 - Present (2 years 8 months)

Built a core payment API layer using Node.js and Java, implementing OAuth 2.0/JWT auth with SQL Server persistence and Redis caching to achieve sub-200ms response times. Migrated storefronts to a headless Next.js architecture and shipped PCI DSS-aligned healthcare payment workflows plus AI-driven education personalization and multi-turn LLM chat support.

Node Java OAuth 2.0 JWT SQL Server Redis Next.js Azure OpenAI PCI DSS

Senior Software Engineer

Stripe

Jun 2020 - Sep 2023 (3 years 3 months)

Developed Node.js and Java backend services for Stripe Tax, using Kafka-based event propagation and PostgreSQL to support global tax workflows across 30+ countries. Delivered Payment Links with React/TypeScript plus real-time WebSocket payment status updates, and integrated scikit-learn fraud detection into transaction scoring pipelines.

Node Java React TypeScript Apache Kafka PostgreSQL WebSockets scikit learn Redshift Snowflake

Senior Full Stack Developer

Shopify

Jul 2018 - May 2020 (1 year 10 months)

Built Node.js microservices behind Shopify Payments and Stripe Connect webhook delivery, supporting payout scheduling and payment method management with sub-300ms webhook response times. Hardened the checkout pipeline using Node.js throttling and Redis rate limiting, and delivered per-tenant checkout scripting and Admin UI features with React/TypeScript and Redux.

Node React TypeScript Redux Redis MySQL PostgreSQL Shopify Payments Webhooks MongoDB Performance Optimization

Full Stack Developer

Walmart

Dec 2014 - Jun 2018 (3 years 6 months)

Implemented the Walmart Pay transaction layer using Node.js and Java, handling QR token generation and payment initiation/in-confirmation via integrated backend services. Extracted services from a tightly coupled monolith into a Pangaea microservices effort and built React-based product search/recommendation experiences with Elasticsearch and MongoDB.

Node Java PostgreSQL Elasticsearch Redis React MongoDB Microservices Architecture Distributed Systems API Design

Web Developer

Affirm

Oct 2012 - Nov 2014 (2 years 1 month)

Built Affirm merchant embed widgets with isolated JavaScript/Angular.js, integrating Node.js and Java Spring backend APIs to deliver BNPL financing at point of sale. Implemented an installment plan engine in Node.js and Java Spring with APR disclosure and payment scheduling, and integrated credit bureau and identity verification APIs to enable real-time underwriting.