Fabio Couto
Verified Expert in Engineering
Front-end Developer
Joinville - State of Santa Catarina, Brazil
Toptal member since April 5, 2018
Fabio is a full-stack senior developer with two decades of experience developing on all the major platforms and tech stacks. He has mastered .NET, the front end, and Android. He's worked in a variety of technology and business areas, such as intelligent chatbots, market risk-management software, big data web systems, cloud eCommerce platforms, payment gateways, and integrations. Fabio's passions are AI, games, and the exploration of new businesses.
Portfolio
Experience
- Front-end - 15 years
- JavaScript - 15 years
- C# - 15 years
- Node.js - 10 years
- Git - 5 years
- React - 5 years
- Kubernetes - 5 years
- Google Cloud Platform (GCP) - 3 years
Preferred Environment
Visual Studio Code (VS Code), IntelliJ IDEA, MacOS, Cursor AI, Windsurf
The most amazing...
...solution I’ve developed was an omnichannel support chat that seamlessly integrated with WhatsApp, MS Messenger, Telegram, and multiple AI agents.
Work Experience
(React+Data Visualization) Front-end Engineer
SynVo, LLC
- Architected a module-and-phase system aligned with Hume AI tools, allowing each interview module to define ordered phases, transition logic, and independently configurable prompts.
- Developed a full administration application from scratch using Next.js and NestJS to manage interviews, prompts, modules, phases, and supporting business entities.
- Built a WebSocket communication layer that synchronized the front end with a Python service while coordinating the service’s real-time connection to Hume AI.
AI Integration Consultant / Senior Full-stack Engineer
WaterFowlAI - BlindBookAI
- Re-architected a Flutter and Supabase application by building a React-based administration platform integrated with the existing back end and data model.
- Established an agentic AI development workflow using Claude Code and Claude Design, with reusable commands, agents, project guidance, and engineering conventions.
- Introduced spec-driven development to convert product requirements into structured specifications, implementation plans, and verifiable development tasks.
AI Specialist / Senior Full-stack Engineer
Cred
- Helped establish a spec-driven software development lifecycle, introducing structured specifications, implementation planning, and AI-assisted engineering practices across the team.
- Developed internal tools and maintained the outreach module, including an AI-assisted email-writing feature that helped users create personalized outreach content.
- Architected and led the development of a unified view system from scratch, coordinating other senior engineers and transforming application pages, reports, and dashboards into configurable interfaces rendered from reusable building blocks.
- Enabled users to customize layouts, views, reports, and dashboards according to their workflows, with AI assistance for generating new pages, configurations, and data-driven experiences.
Supabase/TypeScript Back-end Developer
Steader LLC
- Re-architected and migrated FlutterFlow web and mobile applications to React, TypeScript, and Capacitor, consolidating the product around a reusable cross-platform codebase.
- Designed and delivered a complex marketplace onboarding architecture integrating Stripe Connect, connected accounts with TaxCloud tax registration and calculation workflows.
- Introduced an AI-assisted software development workflow using Cursor rules, then evolved it to Claude Code with reusable commands, specialized agents, and engineering skills.
React and Node.js Senior Full-stack Developer
Waverly Ventures LLC
- Developed a semantic search in a publications database using vertical DB features of PostgreSQL.
- Migrated an app and data from Strapi to Supabase.
- Launched and maintained a new version of the app using Prisma, Supabase, and DigitalOcean for a Node.js back end.
Senior Full-stack Developer
Booking.com
- Maintained one of the largest Perl codebases in the world; also earned a Perl certification.
- Contributed to one of the most important search engines worldwide.
- Made heavy use of a data-driven development framework.
- Handled A/B test-oriented programming. All features implemented utilized A/B testing.
- Developed in-house SOA solutions. Introduced migration from legacy monolith to microservices and microfrontend architectures.
(React+Java Spring Boot) Senior Full-stack Developer
ConnectED Labs Solutions Inc.
- Built a collaborative WebSocket-based whiteboard that synchronized interactions between multiple users in real time within a React classroom interface integrated with a Unity WebGL application.
- Optimized the React application by replacing inefficient shared state with Redux and domain-specific slices, reducing unnecessary renders, memory pressure, and UI performance issues.
- Led collaboration between the Unity and web teams, improving engineering practices, technical alignment, and delivery across an immersive real-time classroom platform.
React/Next.js/Tailwind Front-end Developer
Octue Ltd.
- Implemented an advanced Stripe Connect integration in Django, supporting connected-account onboarding, account management, and payment workflows through a React front end.
- Migrated the React front end to strongly typed TypeScript clients generated automatically from the Strawberry GraphQL schema, reducing manually maintained API integration code.
- Refactored GraphQL queries to use reusable fragments and generated client operations, improving type safety, consistency, and maintainability across front-end data flows.
Senior Full-stack Developer
VTEX
- Planned and implemented the payment gateway protocol, which was used to scale the development of new payment integrations worldwide with the community.
- Implemented extensive scaling and load automated tests with Apache JMeter.
- Provided continuous support for the cloud platform.
- Developed integrations with worldwide payment gateways.
- Implemented an adaptation for a PCI-compliant process.
Lead Full-stack Developer
Tasken
- Architected and led the development of a cloud-based credit recovery solution.
- Supported the architecture of an omnichannel chat solution.
- Developed an AI chat attendant with IBM Watson and Wit.ai.
- Integrated WhatsApp, MSN Messenger, and Telegram channels.
- Implemented a batch import process that had millions of transactions by the minute.
Senior Full-stack Software Developer
Cortex
- Acted as the senior developer of a cloud solution for BI systems.
- Built an ETL solution for bulk data entry processes.
- Studied and implemented new technologies for internal development process improvements.
- Implemented Agile development methods like Scrum and Kanban.
- Automated end-to-end and user tests with Sikuli and Karma.
Software Developer | Finance and Risk Management Consultant
Accenture
- Developed and maintained key modules like market risk, Basileia II and III, credit risk, the platform general infrastructure, and license management.
- Migrated a complex risk management application from Delphi to C#.
- Evolved the monolith system to a three-layer architecture.
- Developed a state-of-the-art solution for anti-fraud systems.
- Led risk management consulting projects for large Brazilian companies.
Developer
Lab245 Software
- Acted as one of the key programmers of the company's main solution.
- Developed DLL libraries, APIs, OCX and Active X’s components, and client applications.
- Supported and implemented GED and workflow systems.
- Used advanced SQL Server and Oracle queries with an optimized performance.
- Created a complex workflow structure solution for control of the document lifecycle.
Experience
Chega+
https://www.chegamaisapp.comMutual
https://mutual.clubKajabi Customization for Course Platform
https://pickupmusic.comMY ROLE
• Applied some core programming concepts like cache, indexing, and deep knowledge of REST to come up with many complex workarounds to fill the gaps created by Kajabi limitations.
• Used JavaScript deep knowledge to reverse-engineer a 3rd-party video player library and be able to fix external dependency bugs.
• Developed a carousel (and grid components) for the client to be used in Kajabi templates: it is totally customizable, fits all screen sizes, and is platform agnostic.
• Designed and implemented automated processes to bulk-use Kajabi's admin panel. Developed a separate dashboard app to manage the automation.
Edtech with 3D Classroom Solution on Web
https://metalingo.caI joined the team as a senior full-stack developer who supported ongoing projects, focusing on bugs, stability, and new feature development:
• Developed and maintained both the front-end and back-end components.
• Worked on bug fixing, ensuring platform stability, and implementing new features.
• Led the implementation of AI features, particularly those aimed at the private sector.
• Collaborated with the design team to translate designs into functional features.
• Conducted code reviews and provided mentorship to junior developers.
• Troubleshooted and debugged issues to ensure the stability and reliability of the application.
• Handled data integration and management, ensuring smooth data upload processes for schools and colleges.
Platform Repository to Manage JSON Schema
https://strands.octue.comI contributed as a senior full-stack developer and performed the following tasks:
• Migration of front-end GraphQL client from React-Relay to Apollo Client
• Implementation of Stripe payment flow for complex organisation-level seats recurrent subscriptions
• Revamp of front-end UI/UX (React)
Education
Master's Degree in Artificial Intelligence
PPGI and NCE | Universidade Federal do Rio de Janeiro - Rio de Janeiro, Brazil
Post Graduate Degree in Software Project Management
CCE | Pontifical Catholic University of Rio de Janeiro - Rio de Janeiro, Brazil
Bachelor's Degree in Computer Science
UFRJ | Universidade Federal do Rio de Janeiro - Rio de Janeiro, Brazil
Skills
Libraries/APIs
React, jQuery, Node.js, Google APIs, Vue, Liquid, Stripe, Stripe API, Shopify API, Google Sheets API, WhatsApp API, REST APIs, Playwright, API Development, React Redux, Claude API, React Testing Library, Facebook API, D3.js, Vuex, React Query, React Router, GraphQL API, OpenAI API, Puppeteer, OpenAPI, Web API, Nightwatch.js, Sikuli, WebRTC, Azure API Management, Jira REST API, Django-allauth
Tools
Git, Amazon Elastic Container Service (ECS), Amazon ElastiCache, Trello, Tableau, GitLab, Figma, Google Analytics, Google Sheets, GitHub, Webpack, Amazon Simple Queue Service (SQS), React Apollo, JSON Schema, Jira, Bitbucket, Claude Code, Asana, Pentaho Data Integration (Kettle), IBM Watson, Watson Developer Cloud SDK, Apache Maven, GitLab CI/CD, Kafka Streams, Redux Toolkit, Auth0, ChatGPT, RabbitMQ, Shadcn, GitHub CLI, Figma to HTML, Sentry, Claude, IntelliJ IDEA, CVS, Subversion (SVN), Karma, Apache JMeter, Terraform, Prisma, Babel, Windsurf, Expo, Claude Agent SDK
Languages
Java, C#.NET, HTML5, CSS4, Active Server Pages (ASP), VB, Perl, JavaScript, C#, Python, Liquid Template, CSS, HTML, TypeScript, SQL, GraphQL, Dart, ECMAScript (ES6), Shopify Liquid, Less, Go, PHP, Sass, Rust, Delphi, SCSS, Bash Script, Kotlin, Java 8, Ruby, Prolog, C++, Elixir
Frameworks
.NET, Unity3D, AngularJS, ASP.NET MVC, Flutter, Angular, Redux, Next.js, Express.js, Tailwind CSS, Material UI, Jest, Spring Boot, NestJS, Bootstrap, OAuth 2, Spring, Swagger, JSON Web Tokens (JWT), AWS HA, Bootstrap 3+, React Native, .NET Core, Django, Ruby on Rails (RoR), gRPC, Laravel, Windows Presentation Foundation (WPF), Grails, ASP.NET Core, Flask, Hadoop, Phoenix, Spring Microservice, Selenium, Unity, Agentic Frameworks, Svelte, Cypress
Paradigms
Agile, Scrum, REST, OLAP, Service-oriented Architecture (SOA), Mobile Development, Business Intelligence (BI), MEAN Stack, Requirements Analysis, Test Automation, Microservices, Testing, Object-oriented Programming (OOP), Microservices Architecture, Unit Testing, Object-relational Mapping (ORM), REST API Architecture, Kanban, Test-driven Development (TDD), DevOps, Load Testing, DevSecOps, Continuous Delivery (CD), Continuous Integration (CI), Serverless Architecture, Microfrontends, Search Engine Optimization (SEO), Low-code Development, Behavior-driven Development (BDD), Azure DevOps
Platforms
Android, Amazon Web Services (AWS), Amazon EC2, AWS Elastic Beanstalk, Docker, Kubernetes, Kajabi, Shopify, Mobile, Vercel, Oracle, Google Cloud Platform (GCP), WordPress, AWS Lambda, Firebase, Apache Kafka, Replit, Algolia, PostHog, MacOS, Windows Phone, Pentaho, Azure, Jupyter Notebook, Visual Studio Code (VS Code), Azure Functions, DigitalOcean, Linux, iOS
Storage
Amazon S3 (AWS S3), SQL Server 2016, PostgreSQL, Elasticsearch, MongoDB, Data Integration, Databases, NoSQL, JSON, SQL Server 2017, Redis, SQL Stored Procedures, Database Management, MySQL, Google Cloud, Redis Cache, Amazon DynamoDB, Microsoft SQL Server, Vertica, Azure Queue Storage, Neo4j, Cloud Firestore
Industry Expertise
Project Management, E-learning, Accounting
Other
System Design, Minimum Viable Product (MVP), Amazon Route 53, WCF Web Services, Domain-driven Design (DDD), Front-end, Lean Development, Speech Recognition, Artificial Intelligence (AI), HTML Templates, Chrome Extensions, Stripe Payments, API Integration, APIs, SaaS, Full-stack, System Requirements, Analytics, System Architecture, Data Processing, OpenAI GPT-3 API, Architecture, Technical Leadership, Web Development, Full-stack Development, Cloud, OpenAI GPT-4 API, Cookies, Google Tag Manager, Front-end Development, Software Architecture, Back-end, OpenAI, WhatsApp, Web Scalability, Scalability, Shopify Theme, AI Chatbots, Speech-to-Text (STT), Text-to-Speech (TTS), Front-end Architecture, User Experience (UX), User Interface (UI), Web3, Cloud Architecture, Engineering, Dashboards, Software, Communication, Design Systems, Containers, Message Queues, Solution Architecture, Software as a Service (SaaS), Back-end Development, Serverless, CI/CD Pipelines, API Gateways, MERN Stack, Startups, eCommerce, Generative Artificial Intelligence (GenAI), Prompt Engineering, Supabase, Large-scale Distributed Systems, RESTFul APIs, Tailwind UI, Legacy Code, Migration, Application State Management, RESTful Microservices, GitHub Actions, Authentication, Mobile App Development, Agentic AI, Cursor AI, Webhooks, Data Management, Scaling, AI Tools, Payment APIs, Payments, Third-party Integration, User Experience Design, Static Site Generators, Financing, AI-generated Code, Code Review, Cloud Services, Push Notifications, Agentic Workflow Design, Vibe Coding, Agentic Coding, AI Agent Orchestration, Content Delivery Networks (CDN), Supabase Auth, Integrations, Anthropic SDK, Integration, Amazon API Gateway, Deno, Games, Game AI, Machine Learning, IBM Watson Speech to Text, Data Visualization, Tableau Server, Online Payments, Material Design, Fintech, Generative Pre-trained Transformers (GPT), Llama 2, Big Data, Team Leadership, NextAuth.js, PCI DSS, Payment Gateways, Educational Portals, Education, Large Language Models (LLMs), Shopify Customizations, Conversational AI, Natural Language Processing (NLP), Security, Server-side Rendering (SSR), Infrastructure as Code (IaC), WebSockets, AI Model Training, Amazon RDS, Amazon Redshift, Semantic Search, Vector Databases, Retrieval-augmented Generation (RAG), UI Testing, OAuth, Radix UI, Responsive UI, Learning Management Systems (LMS), AI Integration, AI Agents, Page Speed Optimization, Data Engineering, ActiveCampaign, Agentic RAG Systems, Product Management, Row-level Security (RLS), Amazon EventBridge, CGI, OCX, Windows Communication Foundation (WCF), New Kajabi, Scope Management, Artificial Neural Networks (ANN), Chatbots, CRM APIs, Jetpack Compose, Fine-tuning, Vite, Zustand, Middleware, Multimedia, Finance, FastAPI, Google Calendar, Standardization, Data Build Tool (dbt), Edge Functions, Claude Design
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