Sandro Fernandes, Back-end Developer in Ibiúna - São Paulo, Brazil
Sandro Fernandes

Back-end Developer in Ibiúna - São Paulo, Brazil

Member since May 21, 2014
Sandro is driven by a uniquely strong dedication: he has been an entrepreneur from an early age. With extensive experience developing sustainable solutions and a love of learning new technologies, he constantly seeks new challenges and new opportunities to excel.
Sandro is now available for hire




Ibiúna - São Paulo, Brazil



Preferred Environment

GitHub, MySQL, jQuery, Python, PostgreSQL, React, Django, NGINX, Ubuntu, TypeScript

The most amazing... I've coded are a logo interpreter written in 120 lines of code, a barcode reader on a joystick port, and a full text search for the Hebrew language.


  • Full-stack Developer

    2014 - PRESENT
    Toptal Clients
    • Developed several applications for international companies, from a simple REST app that took three days to develop to a project spanning eight months.
    Technologies: HTML, NGINX, Linux, Node.js, Databases, Windows, React, CSS, jQuery, Django, Python, MacOS, Vue
  • CEO, Lead Developer, DBA

    2007 - 2015
    • Developed a website with two million unique visitors, seven million page views, and a million emails sent per month.
    • Implemented a MySQL database schema with a high availability design in mind.
    • Developed a CMS in Django tailored to Guiadobebe's needs.
    • Installed and configured secure Linux servers back end.
    • Developed applications and improved the site's SEO.
    Technologies: Linux, MySQL, Django, Python, Django-rest-auth, Bash, CSS, HTML, NGINX, Cache, Content Management Systems (CMS), Trade, Google Analytics, Full-stack, API Development, SQL
  • Founder

    1984 - 2015
    Softrent Automação Comercial ltda.
    • Pioneered the use of barcodes in Brazil.
    • Worked as chief developer and organizer.
    • Led the development of solutions for video rental stores, for many years.
    • Gained experience in running a company as a CEO, managing finances and making the main decisions.
    • Trained more than a hundred employees.
    • Performed consulting jobs for many companies.
    Technologies: Relational Databases, Django, Python, Infrastructure, C, Delphi, Assembler, Barcode Library, Clipper
  • Computer Science Teacher (pro bono)

    2005 - 2006
    American School in São Paulo
    • Taught teenagers the fundamentals of computer science.
    • Used Lego Mindstorms to help students learn basic computing.
    • Used a 8086 emulator to demonstrate how a microprocessor works.
    • Used Delphi to build small Windows programs illustrating logic, program flow, output, and more.
    • Graded students by skill level.
    Technologies: Delphi


  • Karaites Learning Center

    A website that allows people to read and listen to biblical and Karaites-related books. The books are generally in English and Hebrew. I enabled a search feature to search for books in both English and Hebrew, and liturgy songs can be played in-app.

    Some challenges were enabling full-text search in Hebrew and synchronizing Hebrew audio books with text.
    I was the developer from the start to the end of the project. I was involved in the back and front ends, server config, and installation.

    Stack: Django, Python, Nginx, PostgreSQL, React, TypeScript

    This was an open source project.

  • Back End to a POS

    Ported a very old back-end for the POS, a Swift application running on an iPad, from Python 2.7 to Python 3.
    I collaborated with another engineering team member, and I developed the front-end.
    The server resources here are optimized, reducing the monthly bill by 60%.
    The dead code was removed.
    An improved Django admin was developed so that users add more control.
    Updated all stacks for the current version.

    Stack used: Django, NGINX, Gunicorn, PostgreSQL, Supervisor

  • Making Surveys Greener

    The company sells licenses to companies that use a remote inspection system. It allows users to avoid travel and its associated expenses, optimizes survey time, and facilitates meetings between experts without the need for travel.

    The system is composed of proprietary hardware, mainly video cameras, and software that runs in a browser.

    Stack: Django, Django REST Framework, SQLite/PostgreSQL, React, Twilio API, Shopify API

  • Dane Roth (via Toptal)

    This is a Chrome extension to search and suggest shows based on the web pages visited.

    Stack: Django for the back end, jQuery and vanilla JavaScript for the front end, PostgreSQL as the relational data, Redis as cache, and Heroku as the hosting provider.

  • Solvencyii Wire (via Toptal)

    Web applications to deal with financial data from European insurance companies.

    Insurance companies provide balances in PDF format. Those are scanned and translated into Excel spreadsheets. And, after human checking, they are imported into a database. From there, many queries are possible in a web UI.

  • Survey System (via Toptal)

    Surveys on drivers from Lyft, Uber, and others. The user uploads a picture of the Lyft app screen to the website, on the background Google Vision API is used to read the text in the screen image. Based on that, some checks are made and some statistics are generated.

    To incentivize the drivers to post, a fee is paid for each week that the drivers upload images. To upload, the driver must have an account. Payments are made using a PayPal account.

    Stack: Flask, React, MongoDB, Heroku, mLab

  • IDS Consulting (via Toptal)

    Acted as a mentor/developer teaching good practices and overall project development.

    Stack: Django, REST Framework, Vue, Vuex, SQLite, Heroku

  • Challenge Your Understanding (via Toptal)

    A project dedicated to supporting high-level discussions about any topic.

    The user may participate in debates—all are moderated, and each idea can have pro/con responses. It's a meritocracy based on votes.

    Stack: Django, Django REST, PostgreSQL, React

  • Content Management System

    Publish/remove content based on time or other criteria.

    Supports automatic content cache, without warm-up, optimization of image sizes and minifying of CSS and JavaScript, or page previews.

    The content is organized in a tree shape and can be moved around using drag-and-drop. The pages include authentication, and plugins may be inserted in the pages. Any data model may be related with any other model.

    The email system is based on templates and integrated with the CMS. The emails sent can collect data such as clicked links and support many other features.

    I will be glad to give you a demonstration!

  • Flight Vector Tracker (via Toptal)

    Control pilots’ flight time, certifications, training, etc., in a single-page app able to work offline, syncing data when an internet connection is available. Desktop, iPad, and cell phone compatible.

  • CHEP Aerospace (via Toptal)

    Redis cache for a Python application controlling thousands of ULDs and airplane flights.

  • Smarking, Inc. (via Toptal)

    Django REST API to allow clients to get data.

  • CFMC | Qualtrics Surveys (via Toptal)

    A Django REST framework application to tally surveys in a remote PHP client, using AWS Linux and EC2.

  • A Portuguese to Portuguese Dictionary in React

    Features that are calculated and displayed in this product include given meanings to words, verb conjugation, sound-a-like words, anagrams, syllable division, and plurals. Also, spelling localization is included for Portuguese of Portugal and Brazil.

    Stack: Django, Django REST, NGINX, Node.js, React

  • Ad Server

    Tally served banners and ads.

    Controlling campaigns, by client, by time, quantity, and user geolocation. Reports are generated by client, ad campaigns, click rate, etc.

    Stack: Python, Django, jQuery, MySQL, Ubuntu, Nginx, DigitalOcean

  • Newsletter Series

    The goal of the system is to automatically send a series of newsletters.

    The system works based on a timeline around a main event. The timeline may precede and/or succeed the event. Each milestone is associated with an email template and a number of days before or after the main event. On the due date, the email is sent.

    The email templates are integrated with user profiles so that message can be personalized.

    Stack: Python, Django, jQuery, Cron, Bash, MySQL, Nginx

  • UprisingTec

    I ported a Python 2.7 application to Python 3.8. This application collects data from several internet resources using APIs, and all the data is organized in a relational database. The goal was to select candidates for school donations.

    Various clients, including universities, paid for this information.


  • Languages

    Python 3, SQL, HTML5, CSS3, JavaScript, HTML, Python, CSS, Python 2, TypeScript, Bash
  • Frameworks

    Django, Django REST Framework
  • Libraries/APIs

    API Development, jQuery, React, REST APIs, Node.js
  • Tools

    NGINX, PyCharm, GitHub, Pytest, Jenkins, Microsoft Excel, Git, Google Analytics, Supervisord
  • Paradigms

    REST, Object-oriented Programming (OOP), HIPAA Compliance, ETL
  • Platforms

    Ubuntu, DigitalOcean, Linux, Firebase, MacOS, Windows
  • Storage

    MySQL, Redis, MongoDB, PostgreSQL, Relational Databases, Databases, Neo4j, SQLite, Cache
  • Other

    Back-end, APIs, Ubuntu Server, Content Management Systems (CMS), Full-stack, Full-stack Development, PWA, Progressive Web Applications (PWA), Data Handling, Health Policy, Trade, Physics, Mathematics, Lab, Reports, Gunicorn, Open Source


  • Bachelor of Science Degree in Physics
    1980 - 1984
    Fundação Educacional de Bauru - São Paulo, Brasil


  • Node.js, Express, MongoDB & More: The Complete Bootcamp 2023
  • OpenAPI: Beginner to Guru
  • HIPAA Privacy & Security for Business Associates
    MARCH 2019 - PRESENT
    Evolve E-learning Solution
  • Complete Guide to TensorFlow for Deep Learning
  • The Complete React Native and Redux Course
  • Functional Programming with Python
  • Asynchronous JavaScript
    JULY 2018 - PRESENT
  • Toptal React Academy
    JULY 2018 - PRESENT
  • ES6 JavaScript: The Complete Developer's Guide

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