Fernando Guillen

Building Business Success: Web Projects and Technical Architectures

Hello. I am Fernando. I am originally from Spain, but I've lived in Berlin for the last decade. I am an experienced full-stack web developer with more than 20 years of substantial background building big and small web products. I can help you build the web product and technical architecture your business needs.

Full-stack senior web developer specializing in Ruby on Rails and associated technologies.

I specialize in getting web projects off the ground, guiding them from design concept to fully functional applications. I focus on ensuring production quality while maintaining fast development cycles and rapid feedback loops (deliver fast and iterate). As a senior developer position, I have worked for startups, large corporations, and personal entrepreneurial ventures, contributing either as an individual developer or as part of engineering teams of varying sizes, often taking on leadership roles and influencing architectural decisions.

Most recently, as Co-founder and CTO of a rapidly growing technology company, I was hands-on directing the implementation from scratch of an architecture that now supports more than 100K requests/min and a business of 8 figures yearly—leading the technology decisions of a team of ~80 members. The architecture was acquired in 2022 by an international company.

While my primary expertise lies in Rails applications, I have solid exposure to the entire web development stack.

Over time, I’ve been responsible for a range of tasks, including prototyping, implementing CI-based deployment processes, managing cloud-based servers, front-end development, agile/scrum team management, collaboration with product teams, C-level executive decision-making, microservices architecture implementation, handling high-traffic sites, fraud prevention, performance monitoring, observability and telemetry, autoscaling, managing terabyte-sized databases, down-time-less extensive database migrations, and API design.

I have extensive experience with various languages such as Python, C#, and Java, as well as familiarity with modern JS frameworks like ReactJS and VueJS.

… However, Ruby remains what I enjoy working the most.

Beyond my technical skills, I possess a keen understanding of business needs, demonstrating the ability to make pragmatic decisions and prioritize business growth and success. I excel at collaborating closely with product, sales, and leadership teams, offering alternatives when necessary, and knowing when to make compromises.

Throughout my career, I’ve had the privilege of working alongside incredibly talented individuals from whom I’ve learned and grown. I owe much of my knowledge and skills to the exceptional teams I’ve been a part of and the broader open-source and web development communities, particularly those centered around Ruby.

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