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Senior Full Stack Engineer with 8+ years of experience building scalable web applications using Python, React, Next.js, and Node.js. Experienced in designing REST APIs, modern frontend architectures, cloud deployment, and AI-powered applications using OpenAI and LangChain. Focused on building reliable software that improves user experience and solves real business problems, with a strong background in authentication & security, database management, performance optimization, testing, CI/CD automation, and third-party API integrations.…Senior Full Stack Engineer with 8+ years of experience building scalable web applications using Python, React, Next.js, and Node.js. Experienced in designing REST APIs, modern frontend architectures, cloud deployment, and AI-powered applications using OpenAI and LangChain. Focused on building reliable software that improves user experience and solves real business problems, with a strong background in authentication & security, database management, performance optimization, testing, CI/CD automation, and third-party API integrations.

Sebastian Leal

Full Stack Developer, Web Developer, AI Developer, +5

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Senior Full Stack Engineer with 8+ years of experience building scalable web applications using Python, React, Next.js, and Node.js. Experienced in designing REST APIs, modern frontend architectures, cloud deployment, and AI-powered applications using OpenAI and LangChain. Focused on building reliable software that improves user experience and solves real business problems, with a strong background in authentication & security, database management, performance optimization, testing, CI/CD automation, and third-party API integrations.…Senior Full Stack Engineer with 8+ years of experience building scalable web applications using Python, React, Next.js, and Node.js. Experienced in designing REST APIs, modern frontend architectures, cloud deployment, and AI-powered applications using OpenAI and LangChain. Focused on building reliable software that improves user experience and solves real business problems, with a strong background in authentication & security, database management, performance optimization, testing, CI/CD automation, and third-party API integrations.

Available to hire

Senior Full Stack Engineer with 8+ years of experience building scalable web applications using Python, React, Next.js, and Node.js. Experienced in designing REST APIs, modern frontend architectures, cloud deployment, and AI-powered applications using OpenAI and LangChain.

Focused on building reliable software that improves user experience and solves real business problems, with a strong background in authentication & security, database management, performance optimization, testing, CI/CD automation, and third-party API integrations.

Skills

Experience Level

Expert

Expert

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Expert

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Intermediate

Intermediate

Intermediate

Language

Work Experience

Senior Full Stack Developer at Train children Chess Academy

January 1, 2021 - Present

Developed five production web applications using TypeScript, React (later migrated to Next.js), Python (Django), Node.js, and PostgreSQL. Built high-performance backend services using Node.js, Express, NestJS, and Django, designing scalable RESTful APIs and GraphQL endpoints for high-volume workloads. Integrated OpenAI, LangChain, LangGraph, and Vapi to build AI assistants, document-processing workflows, content generation tools, and voice-enabled features; improved chatbot response accuracy by 35% using RAG. Designed and optimized complex PostgreSQL schemas, improving query performance by 55% via indexing and query optimization. Containerized applications with Docker for consistent local development and production. Implemented automated testing with Jest, Playwright, and Pytest. Built CI/CD pipelines (GitHub Actions) to automate testing/build validation/deployment, reducing deployment time by 70% and increasing release reliability. Reduced page load times by 35% through code splitting

Full Stack Developer at Playworks

January 1, 2018 - January 1, 2020

Developed and maintained full-stack web applications using Python, MySQL, React.js, HTML5, CSS3, JavaScript, and GitHub for internal operations and administrative workflows. Modernized legacy applications by converting traditional HTML/JavaScript pages into reusable React components, improving maintainability and user experience. Reduced CSS maintenance by 40% through reusable components. Built responsive, mobile-friendly interfaces for consistent cross-browser/device functionality. Implemented WebSocket-based real-time dashboard/notification features while optimizing backend queries and frontend rendering to improve performance. Collaborated with cross-functional teams using GitHub, performed code optimization and production issue resolution, and contributed to continuous enhancements. Assisted with database design and maintenance using MySQL, writing optimized SQL queries and improving data integrity across internal systems.