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João Fernandes Neto
Verified Expert in Engineering
Software Developer
São Paulo - State of São Paulo, Brazil
Toptal member since April 22, 2016
Bio
João is a software engineer with 15+ years of experience building web applications using Django and React. He combines strong technical knowledge with hands-on development. João is passionate about scalable systems, cooperative work, and creating technology that drives positive social change.
Portfolio
Tetra
Amazon S3 (AWS S3), APIs, Back-end, Django, Django REST Framework, Celery...
Bikky
React, PHP, Amazon EC2, Amazon S3 (AWS S3), CSS, Sass, Python, Django...
iSpot.net, Inc.
Git, Gulp, Sass, JavaScript, PHP, WordPress, Web Development, Front-end...
Experience
- Linux - 14 years
- CSS - 13 years
- JavaScript - 10 years
- Git - 10 years
- Python - 8 years
- Node.js - 8 years
- React - 7 years
- Django - 2 years
Preferred Environment
Git, Ubuntu, Cursor AI
The most amazing...
...project I've built was a custom Django/React social-impact marketplace for family farmers.
Work Experience
Senior Software Engineer
2023 - 2025
Tetra
- Built and maintained core web applications across the back end, APIs, integrations, and the front end, enabling Tetra’s expansion from Massachusetts to New York.
- Led front-end architecture, introducing RTK Query, front-end testing, and major refactors that improved reliability and maintainability.
- Developed new product surfaces, including contractor and customer dashboards, and a walkthrough tool for installation visits.
- Integrated internal systems with Monday and Salesforce, streamlining communication between sales, operations, and installation teams.
- Improved quoting and onboarding flows, reducing user friction and providing sales teams with more complete and accurate client data.
- Mentored new engineers through code reviews and onboarding, raising front-end code quality and consistency.
Technologies: Amazon S3 (AWS S3), APIs, Back-end, Django, Django REST Framework, Celery, Monday.com, Salesforce, Front-end, React, RTK Query, Material UI, PostgreSQL, Full-stack, Next.js
Full-stack Developer
2021 - 2022
Bikky
- Assisted in pivoting from a customer segmentation and marketing orchestration tool to a customer data platform (CDP).
- Implemented the front end by rewriting most of it by myself and following the designs made by the customer. I also updated very old dependencies.
- Migrated the front-end state management library from Redux to React Query.
- Helped migrate the back end from PHP with Laravel to Python with Django and Django REST Framework.
- Added views, serializers, models, filters, and pagination in the back end, all of which were accompanied by tests.
Technologies: React, PHP, Amazon EC2, Amazon S3 (AWS S3), CSS, Sass, Python, Django, Django REST Framework, PostgreSQL, HTML, Testing, Git, Antd, APIs, Back-end, SQL, Web Development, Full-stack, Front-end, Laravel, Next.js
Web Developer
2019 - 2020
iSpot.net, Inc.
- Created two WordPress themes with the help of my teammates.
- Maintained WordPress plugins and themes that already existed.
- Created front-end code for the above projects using JavaScript, Sass, and HTML.
Technologies: Git, Gulp, Sass, JavaScript, PHP, WordPress, Web Development, Front-end, Back-end, Full-stack
Web Developer
2018 - 2019
Bain & Company
- Created the front end of a web application to manage consultant training using React.
- Built an API for the above app using Node.js, Express, and MongoDB.
- Used Amazon EC2 and S3 to deploy the training app.
Technologies: Amazon Web Services (AWS), Node.js, MongoDB, Express.js, Git, Linux, Amazon S3 (AWS S3), Amazon EC2, React, APIs, Back-end, Web Development, Front-end, Full-stack
Extension Developer
2017 - 2019
Omnivision Media, LLC
- Developed a Chrome/Firefox extension to apply discount coupons to retailer's checkout pages.
Technologies: Git, HTML, CSS, JavaScript, Chrome Extensions, Web Development
Web Developer
2017 - 2018
Accelera Technologies
- Developed a simulator for power consumption using React.
- Created a page with React to explain the fields of different format of power bills.
- Built some web pages from a given design using only HTML, Sass, and jQuery.
Technologies: Git, HTML, CSS, jQuery, JavaScript, React, Web Development, Front-end
Developer
2017 - 2017
Galatea Design
- Created a customized rich-text editor from scratch using React, Redux, and Draft.js.
- Created React components for an existing application, which included some pages with API calls.
- Fixed small bugs on the pre-existing Node.js back-end.
Technologies: Node.js, MongoDB, Express.js, Git, Draft.js, Redux, React, APIs, Back-end, Web Development, Front-end, Full-stack
React Web Developer
2016 - 2016
Smarking
- Created reusable React components, including charts and graphs that used amCharts. Also created some page-level components to access the API data and manipulated it to be shown as charts.
- Developed Mocha unit tests, with Chai as the assertion library.
- Wrote HTML emails, first manually then with the MJML email framework.
- Developed a Python module to send emails with Mandrill.
- Participated in the code review process, which improved my code a lot in terms of maintainability and readability.
Technologies: Git, Python, CoffeeScript, React, Web Development, Full-stack, Front-end, Back-end
Software Developer
2015 - 2015
ImageTec
- Created an apartment manager helper platform from scratch.
Technologies: Node.js, MongoDB, Express.js, Git, Linux, React, JavaScript, APIs, Back-end, Web Development
Software Developer
2014 - 2014
Hacklab
- Worked on a pre-existing Java-based script writing tool.
- Built a prototype for a new version of the script writing tool with NW.js.
- Created a mobile PhoneGap app, with Google Maps API and AngularJS.
- Maintained a big WordPress site, doing some improvements and bug fixes.
Technologies: Node.js, MongoDB, Linux, WordPress, PHP, NW.js, JavaScript, Java, Web Development
Software Developer
2009 - 2012
Touch Health
- Worked on a platform used by medical labs to charge medical insurance companies.
- Worked on a high level programming language, used as a module in another projects to give flexibility to medical forms.
- Worked on a decentralized stock management tool.
Technologies: Linux, JavaScript, Java, Back-end, SQL, Web Development
Education
2007 - 2013
Bachelor's Degree in Computer Engineering
Polytechnic School of the University of São Paulo - São Paulo
Skills
Libraries/APIs
React, Node.js, jQuery, NW.js, Antd, React DnD
Tools
Git, Sublime Text, Gulp, Celery, RTK Query
Languages
CSS, JavaScript, HTML, SQL, HTML5, CoffeeScript, Python, Sass, PHP, Java
Frameworks
Express.js, Django, Redux, Draft.js, Django REST Framework, Laravel, Material UI, Next.js
Platforms
Ubuntu, Amazon Web Services (AWS), Linux, Amazon EC2, WordPress, Heroku, Salesforce
Storage
MongoDB, Amazon S3 (AWS S3), PostgreSQL
Paradigms
Testing
Other
Web Development, APIs, Back-end, Full-stack, Front-end, Full-stack Development, Front-end Development, Back-end Development, Chrome Extensions, Cursor AI, Monday.com
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