Open to opportunities

Robert Castillo

@robertcastillo

Message

Senior full-stack engineer building scalable SaaS and customer-focused APIs.

United States

Message

What I'm looking for

I’m looking to contribute strategic thinking and hands-on engineering to accelerate product growth, focusing on scalable SaaS, resilient APIs, and customer-focused delivery. I want cross-functional teamwork where code quality, reliability, and mentoring are valued.

I’m a Senior Full Stack Software Engineer with 7+ years of experience building scalable SaaS platforms, focused on delivering high-quality, customer-focused products in fast-paced environments.

I bring end-to-end ownership—from responsive frontend interfaces to resilient backend systems—translating product needs into real features, RESTful APIs, and microservices that support new capabilities and external integrations.

Over my roles, I’ve optimized performance by improving database queries and API endpoints, strengthened reliability through comprehensive unit and integration tests, and modernized delivery with automated testing pipelines and CI/CD workflows in GitLab.

I also invest in team excellence through code reviews and mentoring, collaborating cross-functionally to drive product adoption and retention while staying methodical and collaborative in agile execution.

Experience

Work history, roles, and key accomplishments

Software Engineer

WebstaurantStore

Oct 2025 - Apr 2026 (6 months)

Developed and maintained full-stack features for a high-traffic e-commerce platform, ensuring responsive UI and robust backend services. Optimized database queries and API endpoints, wrote unit and integration tests, and contributed to code reviews and architectural discussions.

Full Stack React API Development REST APIs Unit Testing Integration Testing Agile Delivery Code Review Performance Optimization

Software Developer

Oracle

Mar 2022 - Sep 2025 (3 years 6 months)

Built and scaled customer-facing SaaS applications using Python, Flask, JavaScript, and TypeScript with an emphasis on performance and UX. Designed RESTful APIs and microservices, implemented CI/CD with GitLab, and mentored developers through pair programming and code reviews.

Python Flask JavaScript TypeScript RESTful APIs Microservices

Software Engineer

STI Computer Services

Nov 2021 - Mar 2022 (4 months)

Engineered full-stack web applications for enterprise clients using C#, .NET Core, ASP.NET Web API, Angular, and TypeScript. Built reusable Angular components, developed and consumed REST APIs, and maintained unit tests to support robustness and refactoring.

C#.NET Core Web APIs REST APIs Angular TypeScript Unit Testing Full Stack Web Development Agile Delivery

Software Developer

TekSynap

Oct 2020 - Nov 2021 (1 year 1 month)

Developed and enhanced features for a government-facing web application using C#, .NET Framework, React.js, and Redux. Designed and optimized SQL schemas and queries, implemented RESTful APIs, authored unit tests, and supported production issues in a remote agile environment.

C#.NET Framework React Redux SQL RESTful APIs Unit Testing State Management Production Support

Junior Software Developer

Gateway Ticketing Systems, Inc.

Apr 2019 - Jun 2020 (1 year 2 months)

Built automated test suites for ticketing systems using C#, Selenium, and .NET Framework to reduce manual testing and catch defects early. Maintained legacy Borland Delphi code, documented test cases and automation frameworks, and collaborated with developers in sprint planning and retrospectives.

C#Selenium .NET Framework Automated Testing Borland Delphi Test Case Documentation Legacy System Support