Leonel is available for hire
Hire LeonelLeonel Machava
Verified Expert in Engineering
JavaScript Developer
Maputo, Maputo City, Mozambique
Toptal member since December 2, 2015
Bio
Leonel is a seasoned full-stack engineer with 16+ years of experience, specializing in JavaScript (React, Next.js, Node.js, TypeScript) and Python. He excels at system architecture, leading cross-functional teams, and delivering innovative solutions, including AI-driven applications and scalable, high-performance platforms.
Portfolio
Al Tayer Group
JavaScript, React, Node.js, Full-stack, RabbitMQ, Elasticsearch, Apache Kafka...
SystemDesigner
Shadcn, Next.js, TypeScript, Python, OpenAI API, Anthropic, Llama 3...
Eventual Holding Inc.
TypeScript, JavaScript, React, Graphs, SCSS, Next.js, Auth0, Stripe Checkout...
Experience
- JavaScript - 15 years
- System Architecture - 14 years
- Node.js - 12 years
- React - 9 years
- TypeScript - 6 years
- Next.js - 5 years
- Artificial Intelligence (AI) - 4 years
- OpenAI API - 3 years
Preferred Environment
Node.js, WebStorm, TypeScript, React, Next.js, Python, Cursor AI, Large Language Models (LLMs), AI Agents, React Native
The most amazing...
...thing I have built is a browser-based coding language and an AI-driven no-code/low-code platform to rapidly create apps from natural language descriptions.
Work Experience
Senior Full-stack Developer
2025 - PRESENT
Al Tayer Group
- Led development of scalable eCommerce features for Ounass, including PLP ranking optimization using behavioral signals (CTR, CR, GMV, newness), improving product relevance, and conversion.
- Built and optimized a custom video player (HLS.js-based) to enforce high-quality playback (e.g., 720p+) while preserving adaptive streaming and minimizing bundle size impact.
- Collaborated closely with product, front-end, mobile (iOS), and back-end teams to deliver key initiatives, including storefront migration to a new design system and implementation of backend-driven merchandising logic with OpenSearch.
Technologies: JavaScript, React, Node.js, Full-stack, RabbitMQ, Elasticsearch, Apache Kafka, Express.js, PostgreSQL, MySQL, Microservices, Magento, Redis, Amazon OpenSearch, Vector Databases
Co-founder | CTO
2024 - PRESENT
SystemDesigner
- Built an AI-powered, low-code SaaS platform that empowers users to visually create web apps through intuitive drag-and-drop and natural language instructions.
- Designed and developed a scalable, intuitive user interface enabling rapid app creation through visual and AI-assisted workflows.
- Implemented powerful data modeling and logic-building capabilities, simplifying app development for users without extensive programming skills.
- Defined an innovative architecture, ensuring performance, scalability, and competitiveness among leading low-code platforms.
Technologies: Shadcn, Next.js, TypeScript, Python, OpenAI API, Anthropic, Llama 3, Software as a Service (SaaS), Cloudflare, Tailwind CSS, Artificial Intelligence (AI), Image Generation, AI Agents, Large Language Models (LLMs), Agentic AI
Lead Front-end Engineer
2025 - 2025
Eventual Holding Inc.
- Led the complete rebuild of the EventualClimate front end using Next.js and TypeScript, delivering a modern, scalable, and future-ready architecture.
- Worked closely with the CTO and CEO to shape product direction, refine user flows, and prioritize high-impact improvements.
- Implemented a full analytics layer in the front end, integrating PostHog, Facebook Pixel, and other tracking tools to support product insights and growth initiatives.
- Introduced Storybook to document components, improve consistency, and streamline communication between engineering and design.
- Implemented unit, integration, and end-to-end testing, resulting in higher reliability and development confidence.
- Set up GitHub Actions pipelines for automated CI/CD and contributed key features that improved performance, stability, and overall user experience.
- Designed a structured component and layout system with shared UI primitives, design tokens, route groups, and a feature-based folder organization.
Technologies: TypeScript, JavaScript, React, Graphs, SCSS, Next.js, Auth0, Stripe Checkout, Stripe, GitHub, Playwright, Storybook, Vitest, PostHog, Analytics
AI Engineer
2025 - 2025
Zoom Catalog, LLC
- Built an interactive mockup tool enabling users to drag and position logos on products using depth map estimation and computer graphics.
- Implemented an AI-powered virtual try-on prototype with ACE++ to evaluate product mockups at scale.
- Advised on deployment strategies and infrastructure trade-offs for AI models, helping the client balance performance and cost in early-stage experimentation.
Technologies: Image Generation, Artificial Intelligence (AI), Graphics, Front-end Development, Image Manipulation, Performance, 3D Graphics, 2D Graphics, Stable Diffusion, Vue, ComfyUI, Flux
Senior Software Engineer
2022 - 2023
Patron Technology, Inc.
- Contributed to the modernization of a no-code platform powering mobile apps for major events like Coachella, NHL, and NY Comic Con.
- Revamped key front-end modules using Vue.js and TypeScript for improved UX and performance.
- Built an advanced interactive maps feature to enhance attendee navigation and event engagement.
- Contributed to back-end development with Django, supporting scalable APIs and data flows.
- Collaborated across a distributed team, ensuring smooth integration and fast iteration in a high-paced environment.
Technologies: JavaScript, Front-end, Front-end Development, Responsive UI, MVC Design, CSS, Vue, Django, TypeScript
Technical Lead
2021 - 2023
Luminskin
- Oversaw a cross-functional team of seven software engineers and five QA engineers for Lumin, Pangaea Holdings' largest eCommerce brand, ensuring high-quality deliveries and consistent on-time releases.
- Introduced best practices for system architecture and led significant refactoring efforts, significantly improving the scalability and maintainability of critical eCommerce systems.
- Managed and mentored software engineers, increasing team productivity and product stability and enhancing overall engineering standards through code reviews and continuous mentorship.
- Architected and implemented key technical solutions, including a loyalty and promotions engine, significantly increasing customer retention and average order value.
- Partnered with stakeholders to define development goals and balance technical constraints with business objectives.
- Delivered high-impact releases consistently on schedule, reducing technical debt, improving application reliability, and enabling smoother deployments through strengthened CI/CD processes.
Technologies: Amazon Web Services (AWS), Next.js, TypeScript, Tailwind CSS, Team Leadership, Node.js, Laravel, PostgreSQL, System Architecture, React, PHP, Full-stack, Software Architecture
System Architect | Front-end Engineer
2019 - 2022
CacheFly
- Led the design and implementation of a revamped CDN portal dashboard, significantly improving user experience and system reliability for global customers.
- Maintained and optimized the legacy CDN portal, ensuring continuous, uninterrupted customer access while leading the transition to the modernized dashboard.
- Proactively proposed and implemented enhancements to infrastructure code, earning promotion to system architect.
- Researched and designed critical CDN components, including content distribution strategies, caching layers, and performance monitoring systems.
- Authored detailed technical documentation, facilitating clear communication within the engineering team and enabling smooth onboarding of new engineers.
Technologies: JavaScript, React, Highcharts, Apache, NGINX, PHP, Varnish, System Architecture, Redis, MySQL
React Expert | Full-stack Engineer
2018 - 2019
Toodledo
- Developed and optimized front-end features using React, ensuring seamless integration with the existing back end.
- Expanded my role beyond front-end responsibilities, contributing significant back-end enhancements.
- Conducted research on calendar standards (e.g., iCalendar, CalDAV) to implement robust calendar integration features.
- Improved code maintainability through refactoring and code reviews.
Technologies: PHP, Redux, React, Front-end
Full-stack Developer
2017 - 2019
Keepy
- Developed and maintained iOS and Android apps and back-end systems supporting a user base that grew to over 200,000 active users.
- Expanded the user base by 100,000+ by implementing internationalization (i18n) and launching localized support for the Japanese market.
- Implemented monitoring tools for servers, cache, and message queues, enabling early detection of infrastructure issues and improved reliability.
- Ensured long-term app stability by managing SDK upgrades, renewing certificates, and resolving App Store compliance and compatibility issues.
- Resolved critical bugs and release blockers across mobile platforms, sustaining user engagement and maintaining store rating standards.
Technologies: Node.js, MySQL, Android, Google Play Store, App Store, Swift, Objective-C, Google Cloud Platform (GCP), Java, Amazon Web Services (AWS)
Lead Engineer
2016 - 2019
Loadtap
- Developed an invoicing module that included automatic merging and generation of multiple PDFs.
- Created a real-time tracking module with Google Maps integration.
- Designed and implemented a resilient, fault-tolerant, real-time cell phone tracking solution capable of tracking devices without requiring apps or additional hardware.
- Optimized system availability and performance by transitioning from a monolithic system to a scalable, service-oriented architecture (SOA), significantly increasing reliability.
- Reduced cloud computing costs by 40% by implementing efficient tracking algorithms and optimized resource management strategies.
- Reduced dependence on expensive 3rd-party APIs by developing proprietary solutions, cutting operational expenses, and enhancing service autonomy.
- Conducted extensive research and development to create robust algorithms and data structures for real-time geolocation, reducing latency and improving shipment ETA accuracy.
Technologies: Amazon S3 (AWS S3), SendGrid, MySQL, RethinkDB, Redux, React, AngularJS, PHP, Node.js, Amazon Web Services (AWS), Front-end, Data Visualization, NoSQL, Software Architecture, Full-stack, Software as a Service (SaaS), RabbitMQ, Microservices
Lead Engineer
2017 - 2018
Antena 1 (via Toptal)
- Led a team of developers in a project involving the modernization of their web app and live streaming platform.
- Mentored them regarding security, best practices, future-proof setup, and implementation of new technologies.
- Developed a custom cross-browser audio streaming library.
- Built various React components and back-end features.
- Integrated React with a custom-built audio engine using HTML5 Audio APIs.
- Contributed to the strategy for migrating users and data from the old to the new platform.
- Designed the platform to support server-side rendering.
Technologies: Audio Streaming, HTML5, Node.js, Redux, React, Front-end
Node.js/React Developer
2016 - 2016
Ellement Consulting (via Toptal)
- Developed back-end features using Node.js, Koa, and PostgreSQL.
- Designed and implemented a caching layer using Redis.
- Worked within a team that adopted an agile software development methodology.
- Developed various front-end features wired to the API using React and Redux.
- Developed application reports output as PDF using Latex components.
Technologies: GitHub, Travis CI, Redis, PostgreSQL, Redux, React, ECMAScript (ES6), Node.js, Front-end
Front-end Developer
2016 - 2016
The Bouqs Company (via Toptal)
- Participated in the development of a universal Redux app.
- Worked within a team that adopted an agile software development methodology.
- Reviewed portions of the back end (PHP) to identify the causes of several issues.
- Developed some server-side features using Node.js and Koa.
- Developed a vouchers feature for orders.
- Worked on a subscriptions feature.
Technologies: PrestaShop, Jira, GitHub, Travis CI, Redux, React, Koa, Emacs, Node.js, Front-end
Front-end Developer
2016 - 2016
Lactic Acid, LLC (via Toptal)
- Created a responsive SPA from the ground up using React and Redux.
- Integrated the app with a REST API written in Python.
- Created reusable React components, including a custom chart component using SVG.
- Proposed tools and methodologies to facilitate team collaboration.
- Adopted a modern development workflow including the use of Webpack and ESLint paired with a slightly altered Airbnb style.
Technologies: Semantic UI, Sass, ESLint, Webpack, Redux, React, Node.js, Emacs, Front-end
Software Engineer and Development Manager
2015 - 2016
Maputo Port Development Company
- Enhanced the software development and deployment process.
- Architected and developed software components that integrate with internal ERP systems.
- Designed a solution to interface a company system with customer systems.
- Handled key strategic systems that drive and support the core business of the company.
- Developed an IT dashboard using an SPA front end powered by AngularJS and a Node.js-based REST API.
- Developed an equipment maintenance dashboard using an AngularJS SPA front end backed by an ASP.NET web API.
Technologies: MongoDB, Microsoft SQL Server, .NET, C#, Node.js, JavaScript, Amazon Web Services (AWS), Front-end, NoSQL
Software Engineering Consultant
2013 - 2015
Maputo Port Development Company
- Built a budget management system using PHP, Symfony 2, JavaScript, and jQuery.
- Developed an equipment maintenance management system.
- Enhanced the software development process and refactored existing systems.
- Assisted actively in managing and coordinating software projects.
- Created a custom framework on top of ASP.NET web API and Entity framework.
- Introduced versioning of software development assets using Git.
Technologies: MongoDB, .NET, C#, Microsoft SQL Server, Symfony 2, PHP, AngularJS, Node.js, JavaScript
Software Developer
2008 - 2013
Jembi Health Systems
- Built a cholera tracking system with SMS integration.
- Developed information security policies and business continuity plans.
- Created and deployed a national data capture, aggregation, and reporting system.
- Developed an innovative ICD-10-related mobile app using Java ME.
- Re-engineered and modernized legacy software systems.
- Designed and developed innovative ways of data capture and transmission in low-resource settings.
- Built an Android mobile app concept for teledermatology.
Technologies: Visual Basic .NET (VB.NET), Arduino, Oracle, MySQL, PHP, .NET, JavaScript, Java, Front-end
Experience
Appvise.ai - Full-stack AI App Builder
https://appvise.aiI designed, built, and launched Appvise.ai, an AI platform that turns plain-language ideas into complete web and mobile applications. Appvise generates the full application and provides the database, authentication, hosting, and domain as built-in platform services, so users can build and launch without configuring separate infrastructure.
Gentlebot.ai - Always-on AI Agent Platform
https://gentlebot.aiI designed, built, and launched Gentlebot.ai (currently in beta). Gentlebot enables individuals and teams to create specialized AI agents using plain language. Agents can browse websites, use connected business tools, process files, run code, send messages, and produce reports, spreadsheets, documents, or live web apps. They can work on demand or autonomously through schedules, email, and webhooks, and collaborate within shared workspaces. I led the product end-to-end, including strategy, user experience, engineering, integrations, security, billing, and launch
Education
2005 - 2008
Bachelor's Degree in Computer Science
Eduardo Mondlane University - Maputo, Mozambique
Skills
Libraries/APIs
React, Socket.IO, HTML5 Canvas, REST APIs, jQuery, Node.js, OpenAI API, WebGL, Passport.js, Backbone.js, Highcharts, Vue, Stripe, Playwright
Tools
Webpack, Mocha, Bower, Gulp, Babel, NGINX, Git, Sublime Text, WebStorm, Emacs, Travis CI, GitHub, Jira, SendGrid, Browserify, PrestaShop, Apache, Varnish, Shadcn, Canvas, ComfyUI, Auth0, Stripe Checkout, Vitest, RabbitMQ, Amazon OpenSearch
Languages
ECMAScript (ES6), ES7, JavaScript, TypeScript, HTML5, CSS, Sass, Python, SQL, PHP, C#, Java, Visual Basic .NET (VB.NET), C, Erlang (OTP), C++, Objective-C, Swift, SCSS
Frameworks
Redux, Express.js, Next.js, Flux, Entity, XMPPFramework, Protractor, Symfony 2, ASP.NET Web API, AngularJS, Koa, .NET, iOS SDK, Tailwind CSS, Laravel, Unreal Engine 4, Unreal Engine, Django, LangGraph, React Native
Paradigms
Functional Programming, Test-driven Development (TDD), MVC Design, Microservices
Platforms
Android, Amazon Web Services (AWS), OS X, Ubuntu, Oracle, Arduino, Visual Studio Code (VS Code), Google Cloud Platform (GCP), PostHog, Apache Kafka, Magento
Storage
SQLite, MongoDB, MySQL, Redis, NoSQL, RethinkDB, Amazon S3 (AWS S3), PostgreSQL, Microsoft SQL Server, Databases, Elasticsearch
Other
Front-end, System Architecture, Software Development, Large Language Models (LLMs), XMPP, Data Visualization, AI Agents, Agentic AI, LangChain, ESLint, Semantic UI, Audio Streaming, Ejabberd, Team Leadership, Anthropic, Llama 3, Software as a Service (SaaS), Cloudflare, Artificial Intelligence (AI), 3D Graphics, 3D Games, 2D Graphics, 3D Math, Image Generation, Computer Science, Linear Algebra, Calculus, Algorithms, Data Structures, Probability Theory, Geometry, System Design, Full-stack, Software Architecture, Graphics, Front-end Development, Image Manipulation, Performance, Stable Diffusion, Google Play Store, App Store, Responsive UI, Cursor AI, Graphs, Storybook, Analytics, Vector Databases, Full-stack Development, AI Engineering, AI Automation, Browser Automation
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