Derek O.

Looking for a software engineer who has been through the full lifecycle of real-world software — building, scaling, debugging, securing, modernizing, and rescuing production systems? I’m Derek Owusu-Frimpong, a Senior Ruby on Rails Engineer who has been writing Ruby professionally since 2016. I bring a decade of hands-on Rails experience, the judgment that comes from working on production systems, and the ownership mindset needed to deliver software that actually performs in the real world. As a Top Rated Upwork freelancer with a 100% Job Success Score, I’ve helped startups, founders, and established teams build reliable, secure, and scalable Rails applications. Clients typically bring me in when they need someone who can move fast, understand the codebase quickly, make sound technical decisions, and deliver results without hand-holding. What I Bring to Your Project Ruby on Rails Expertise Since 2016 Rails has been my core stack for years. I’ve worked across greenfield applications, legacy systems, SaaS platforms, internal tools, marketplaces, APIs, and production apps under real customer load. I understand how Rails applications evolve over time — where they slow down, where they become hard to maintain, where security gaps appear, and how to refactor them without breaking the business. Performance Engineering I help Rails applications become faster, leaner, and more reliable. That includes optimizing slow database queries, improving API response times, tuning background jobs, reducing unnecessary memory usage, fixing N+1 queries, adding the right indexes, and improving how systems behave under load. If your users are complaining about slow response times, I can help you find the bottleneck and fix it properly. Secure, Production-Ready Systems Security is not an afterthought in my work. I have experience implementing secure authentication, authorization, API protection, database hardening, security headers, OAuth2 flows, payment integrations, and modern cryptographic techniques including RSA, AES, and PKI. I build systems with a clear focus on protecting user data, reducing risk, and keeping applications reliable in production. Modern Rails: Hotwire, Turbo, Stimulus & Real-Time UX I’m experienced with modern Rails tools including Hotwire, Turbo, Stimulus, and ActionCable, allowing teams to build fast, interactive user experiences without unnecessary JavaScript complexity. For many SaaS and business applications, Rails plus Hotwire is the perfect combination: productive, maintainable, and powerful. Legacy Rails Modernization Many of my projects involve improving existing Rails applications: refactoring difficult code, upgrading dependencies, adding tests, improving deployment workflows, modernizing UI behavior, and making the system easier for teams to maintain. I’m comfortable entering an unfamiliar codebase, understanding what matters, and improving it carefully. Industries I’ve Worked In Fintech, Education, Healthcare, E-commerce, Marketplaces, CRM, SaaS, HR, and Recruitment platforms. Why Clients Work With Me When you hire me, you get more than a developer. You get an engineering partner who takes ownership. I care about clean architecture, maintainable code, clear communication, and measurable business impact. I know when to move fast, when to slow down, when to refactor, and when to avoid over-engineering. I’m comfortable working with founders, technical leads, in-house engineering teams, and non-technical stakeholders. Whether you need someone to build a feature, improve an existing system, review architecture, or debug a painful production issue, I bring my decade of experience to the work. I have been working with Ruby and Rails long enough to know that good software is not just about clever code. It is about reliability, maintainability, performance, security, and trust. Let’s Build Something Reliable, Fast, and Future-Ready If you need a seasoned Ruby on Rails engineer who can understand your product, take ownership of the technical details, and deliver work that holds up in production, I’d be glad to help. Send me a message on Upwork and let’s talk about what you’re building.