Gregory Walker

Built Solidity contract workflows and Node.js backend services for regulated payment operations, supporting large-scale customer accounts and audit-ready transaction histories. Designed an EVM transaction ingestion pipeline with TypeScript and Kafka to process millions of events per day with low-latency settlement status updates. Implemented smart contract security practices (access control, reentrancy protection, and gas optimization) and added robust testing/deployment flows across Ethereum and Polygon using Hardhat. Automated delivery with Azure DevOps, Docker, and Kubernetes, and supported operations with PostgreSQL telemetry, structured logging, and reconciliation jobs.

Owned Node.js services for financial account and transaction workflows handling high concurrency and improving throughput over time. Developed Solidity integration services for EVM-backed payment actions and delivered real-time status updates via WebSocket streams. Created Hardhat and Foundry testing suites for contract behavior, event decoding, and authorization boundaries, improving reliability before production releases. Built a TypeScript gateway with GraphQL and Redis caching, and streamlined CI/CD using Jenkins pipelines for staged releases.

Shaped Node.js service architecture by separating transaction, identity, and notification responsibilities across multiple deployable services at scale. Built Solidity proof-of-concept contracts and Hardhat deployment scripts for EVM payment flows, validating multiple transaction and permission scenarios. Developed REST and GraphQL APIs using Node.js, and integrated Kafka event streams into downstream consumers to reduce redundant data access. Delivered React and Angular user interfaces and automated shared library releases via Jenkins and JFrog Artifactory.

Built Java migration services to convert large volumes of legacy records while preserving financial and regulatory reporting relationships. Developed REXX batch conversion tooling for multiple transformation rules and improved conversion accuracy and automation coverage. Optimized Java ETL jobs to reduce runtime and added validation and rollback utilities to limit rollback incidents across production migration runs. Documented service contracts, data mappings, and deployment procedures used by other engineering teams during later migration efforts.