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I’m a senior full stack developer and technical lead with 12 years of experience building production-grade web and mobile systems in distributed engineering environments. I enjoy turning product requirements into maintainable MVPs, and I’m especially focused on clean architecture, reliable data modeling, and secure authentication/authorization. Across my roles, I’ve delivered scalable event-driven workflows, REST/GraphQL APIs, and robust PostgreSQL data pipelines—often integrating third-party providers through resilient webhook and OAuth-based flows. I also bring practical hands-on leadership: mentoring teammates, strengthening engineering practices like code reviews, testing, CI/CD, and documentation, and continuously optimizing performance and operational reliability.…I’m a senior full stack developer and technical lead with 12 years of experience building production-grade web and mobile systems in distributed engineering environments. I enjoy turning product requirements into maintainable MVPs, and I’m especially focused on clean architecture, reliable data modeling, and secure authentication/authorization. Across my roles, I’ve delivered scalable event-driven workflows, REST/GraphQL APIs, and robust PostgreSQL data pipelines—often integrating third-party providers through resilient webhook and OAuth-based flows. I also bring practical hands-on leadership: mentoring teammates, strengthening engineering practices like code reviews, testing, CI/CD, and documentation, and continuously optimizing performance and operational reliability.

Karol Piotrowski

Full Stack Developer, Software Engineer, Web Developer, +2

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I’m a senior full stack developer and technical lead with 12 years of experience building production-grade web and mobile systems in distributed engineering environments. I enjoy turning product requirements into maintainable MVPs, and I’m especially focused on clean architecture, reliable data modeling, and secure authentication/authorization. Across my roles, I’ve delivered scalable event-driven workflows, REST/GraphQL APIs, and robust PostgreSQL data pipelines—often integrating third-party providers through resilient webhook and OAuth-based flows. I also bring practical hands-on leadership: mentoring teammates, strengthening engineering practices like code reviews, testing, CI/CD, and documentation, and continuously optimizing performance and operational reliability.…I’m a senior full stack developer and technical lead with 12 years of experience building production-grade web and mobile systems in distributed engineering environments. I enjoy turning product requirements into maintainable MVPs, and I’m especially focused on clean architecture, reliable data modeling, and secure authentication/authorization. Across my roles, I’ve delivered scalable event-driven workflows, REST/GraphQL APIs, and robust PostgreSQL data pipelines—often integrating third-party providers through resilient webhook and OAuth-based flows. I also bring practical hands-on leadership: mentoring teammates, strengthening engineering practices like code reviews, testing, CI/CD, and documentation, and continuously optimizing performance and operational reliability.

Available to hire

I’m a senior full stack developer and technical lead with 12 years of experience building production-grade web and mobile systems in distributed engineering environments. I enjoy turning product requirements into maintainable MVPs, and I’m especially focused on clean architecture, reliable data modeling, and secure authentication/authorization.

Across my roles, I’ve delivered scalable event-driven workflows, REST/GraphQL APIs, and robust PostgreSQL data pipelines—often integrating third-party providers through resilient webhook and OAuth-based flows. I also bring practical hands-on leadership: mentoring teammates, strengthening engineering practices like code reviews, testing, CI/CD, and documentation, and continuously optimizing performance and operational reliability.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Intermediate

Intermediate

Language

English

Advanced

Work Experience

Senior Full Stack Developer / Technical Lead at Consensys

June 1, 2021 - Present

Architected scalable financial-data workflows using Node.js, PostgreSQL, and REST APIs to support reliable ingestion, validation, persistence, and downstream processing. Directed full-stack implementation across React Native, Expo, TypeScript, and backend services, translating product requirements into maintainable production architectures. Engineered consent and authorization workflows with explicit state transitions, comprehensive validation, and auditable records; implemented event and audit recording patterns for traceability. Integrated external providers via resilient APIs and webhooks with authentication flows, retries, and structured error handling. Designed normalized PostgreSQL data models covering users, accounts, transactions, permissions, events, and historical records while preserving transactional consistency. Optimized backend queries, API payloads, and asynchronous processing, improving response performance by ~35%. Established code review/testing/documentation practi

Software Engineer at UCB

June 1, 2018 - April 1, 2021

Developed enterprise applications using Node.js, TypeScript, React, and REST APIs to deliver maintainable services for data-intensive business workflows. Refactored backend service boundaries and shared modules to reduce duplication and accelerate delivery across multiple application teams. Built PostgreSQL schemas and migration strategies for transactional workloads, historical records, reporting, and evolving product capabilities. Integrated third-party APIs with OAuth-based authentication, timeout handling, retries, validation, and observability for improved dependency resilience. Implemented granular authorization controls enforcing least-privilege access. Automated unit and integration testing pipelines to increase regression coverage and shorten feedback cycles. Streamlined CI/CD workflows with Git-based automation, deployment validation, environment configuration, and repeatable release procedures. Analyzed performance using logs, metrics, database execution plans, and request

Software Developer at Razor Lnc

March 1, 2014 - May 1, 2018

Built customer-facing applications using JavaScript, React, Node.js, and REST APIs, creating reusable foundations for responsive and maintainable delivery. Implemented server-side business logic and API endpoints to process requests, validate inputs, and persist transactional data to relational databases. Modeled relational datasets with SQL and PostgreSQL, designing normalized tables, indexes, relationships, and migrations. Created reusable frontend components for standardized navigation, forms, validation, state management, and user interactions. Integrated internal applications with external services via REST, authentication mechanisms, request validation, and defensive error-handling patterns. Optimized database queries and backend processing to reduce average response times by ~25% for frequently accessed operations. Introduced automated testing practices covering core business logic, API behavior, validation scenarios, and regression-sensitive workflows; configured Git-based de