Alejandro Castro
@alejandrocastro1
Full-stack MERN developer shipping production web apps with React, Next.js, Node.js, and Supabase.
Costa RicaWhat I'm looking for
I’m a MERN full-stack developer with 2+ years building production web applications using React, Next.js, Node.js, and Supabase. I bring a strong troubleshooting mindset from my trilingual technical support background (EN/ES/PT), so debugging, documentation, and client-facing delivery come naturally to me.
In my freelance work (Jan 2023–Present), I deliver full-stack solutions end-to-end—architecting features, integrating RESTful APIs with JWT authentication and role-based access control, and shipping reliably with Jest/Vitest unit and integration tests. I also improve performance and maintainability using responsive UI with Tailwind CSS and state management with Redux.
My goal is simple: I want to ship real products. I’m actively focused on modern JavaScript, SQL, React ecosystems, and Agile methodologies, and I’m ready to keep building fast, dependable applications that meet real user needs.
Experience
Work history, roles, and key accomplishments
Full-Stack Developer
Freelance
Jan 2023 - Present (3 years 7 months)
Delivered 3+ client websites end-to-end by building full-stack applications with React, Next.js, Node.js, and Supabase, and deploying via CI/CD to production. Improved UI responsiveness and maintainability with Tailwind CSS and Redux, and increased reliability using Jest/Vitest tests with REST API authentication (JWT, role-based access control).
Customer Service Agent
Concentrix
Jul 2021 - Mar 2023 (1 year 8 months)
Increased first-contact resolution for Mac and consumer entertainment onboarding by diagnosing hardware/software conflicts and delivering structured troubleshooting processes, reducing repeat contacts. Improved onboarding quality by documenting technical issue patterns across 100% of interactions to create a reference base for new agents.
Customer Service Agent
Sykes Costa Rica
Jan 2020 - Apr 2020 (3 months)
Accelerated customer onboarding completion by guiding users through multi-step registration and account configuration, reducing inbound follow-up contacts. Resolved Tier 1 technical, billing, and fraud-related issues with high accuracy by following structured escalation paths and maintaining compliance with account security protocols.
Education
Degrees, certifications, and relevant coursework
Udemy
Self-paced React/Next.js & JavaScript Coursework, Web Development
2024 -
Ongoing self-directed courses covering React, Next.js, JavaScript (ES6+), SQL, advanced CSS/Sass, and Agile & Scrum (2024–present).
Private Instruction
Portuguese Language Instruction, Portuguese
Received private Portuguese instruction (September 2023).
American Business Academy
IT Technical Support Certificate, Information Technology Support
Completed an IT Technical Support program (March 2020).
Instituto Nacional de Aprendizaje
Digital Animation & Non-Linear Editing Certificate, Digital Animation & Editing
Studied Digital Animation & Non-Linear Editing (June 2019).
Instituto Nacional de Aprendizaje (INA)
English for Professional Communication Certificate, English
Completed English for Professional Communication (December 2017).
Tech stack
Software and tools used professionally
Availability
Location
Costa RicaAuthorized to work in
Salary expectations
Job categories
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