Artur Tsuda, Software Developer in São Paulo - State of São Paulo, Brazil
Artur Tsuda

Software Developer in São Paulo - State of São Paulo, Brazil

Member since March 8, 2019
Artur is an experienced software engineer with a focus on back-end technologies. Having worked with startups of various sizes and stages, he specializes in building efficient, scalable, and maintainable back-end solutions in Go and Ruby. He believes that great products are built by great teams and not individuals.
Artur is now available for hire




São Paulo - State of São Paulo, Brazil



Preferred Environment

MacOS, Vi, Visual Studio Code

The most amazing...

...project I've done was migrating a large payments system, which involved several teams, a lot of testing, and provided a better user experience.


  • Ruby on Rails Expert

    2021 - 2022
    Toptal Client
    • Implemented several fields and mutations for new GraphQL API.
    • Reviewed peer's code to ensure quality and consistency.
    • Researched, split work into deliverables and estimated duration throughout the whole project.
    Technologies: Amazon Web Services (AWS), Ruby, Ruby on Rails (RoR), Docker, GraphQL, Ruby Performance, Datadog, New Relic
  • Senior Full-stack Developer

    2020 - 2021
    Carnegie Mellon University (through Toptal)
    • Developed the front end and extended back end for CodeLabs, a feature that allows students to upload their code assignments to be executed and graded automatically.
    • Integrated CodeLabs with several other modules in the system (student's gradebook, TAs grading tool).
    • Advised client on architectural decisions for medium-long term.
    • Rewrote the student CLI tool from MVP to production-ready.
    Technologies: Python, Python 3, Django, Django REST Framework, JavaScript, React, HTML, CSS, AWS Lambda, Docker
  • Ruby on Rails Expert

    2019 - 2020
    Toptal (through Toptal)
    • Implemented new authorization for staff users (migration from CanCan to custom solution).
    • Collaborated with three teams throughout the engagement to accelerate project (abilities migration) completion.
    • Engaged directly with stakeholders to get to solutions.
    • Tracked and fixed bugs using Jira as a reporting tool.
    Technologies: Agile Software Development, Ruby on Rails (RoR), Ruby, Docker
  • Full-stack Developer

    2019 - 2019
    Mobilize Networks, Inc. (via Toptal)
    • Rebuilt the front end of a file directory feature, using React with drag-n-drop capabilities.
    • Implemented new events for analytics tracking both in the front end and the back end.
    • Implemented the feature of highlighting posts in the feed from scratch, using React, Redux, and Ruby on Rails as an API.
    • Built an API for the bulk creation of users using Ruby on Rails.
    • Added a new type of a "moderator" role for the authorization system.
    • Refactored the existing back-end push notifications implementation.
    • Performed several smaller maintenance tasks, including CSS changes, bug fixes, changes in email templates, etc.
    Technologies: Redis, Redux, JavaScript, Git, SQL, PostgreSQL, AngularJS, React, Ruby on Rails (RoR), Ruby, Test-driven Development (TDD), Back-end, HTML5, CSS, Amazon Web Services (AWS), Sidekiq, Ruby on Rails 5, Elasticsearch, Ruby on Rails API, REST APIs
  • Software Engineer

    2017 - 2018
    • Ported a Python and Flask webhook service to pure Go to increase the load and ensure a higher throughput.
    • Maintained the Django payment system for Brazilian customers and extended the functionality to support different local market use cases.
    • Migrated Brazil's payment system to a Ruby on Rails global payment system, customized the React front end, built the back-end webhooks, and wrote unit tests.
    • Integrated a third-party email provider for the managed international regions while working closely with the HQ's email marketing team and the other regions' engineering teams.
    • Mentored a software engineering intern with no previous experience in software development; provided coaching, performed weekly one-on-ones, advised on career planning, and performed some pairing.
    • Interviewed and hired four engineers for Brazil's engineering team. Actively participated in the hiring process for the whole international engineering team, assessing CVs, take-home exercises, and in-person interviews.
    Technologies: Redis, PostgreSQL, Test-driven Development (TDD), Redux, Git, SQL, Ruby, Docker, Angular, React, JavaScript, Python, Ruby on Rails (RoR), Go, TypeScript, Back-end, HTML5, CSS, Django, Amazon Web Services (AWS), Sidekiq, Celery, Ruby on Rails 5, Elasticsearch, Ruby on Rails API, REST APIs
  • Full-stack Software Engineer

    2016 - 2017
    por.a.mais.b (Previously Tuneduc)
    • Created a data visualization dashboard using React and Highcharts.
    • Refactored a legacy codebase (Rails and React) for maintainability and added new features.
    • Worked on the prototype for a new web app using the Ruby on Rails API.
    Technologies: Redis, PostgreSQL, Redux, JavaScript, Git, Linux, SQL, Ruby, React, Ruby on Rails (RoR), Test-driven Development (TDD), Back-end, HTML5, CSS, Amazon Web Services (AWS), Sidekiq, Ruby on Rails 4, Elasticsearch, Ruby on Rails API, REST APIs
  • Software Engineer

    2016 - 2016
    • Implemented gamification functionalities inside an existing e-learning platform with Ruby on Rails.
    • Developed a real-time chat for students and mentors.
    • Implemented browser notifications for achievements and new messages.
    Technologies: JavaScript, Git, Linux, SQL, Ruby, Ruby on Rails (RoR), PostgreSQL, Back-end, HTML5, CSS, MySQL, Amazon Web Services (AWS), Sidekiq, Ruby on Rails 4, Ruby on Rails API, REST APIs


  • Payment System Migration

    I maintained the Django codebase for Brazil's payment system during the migration phase to the new global solution (Ruby on Rails) that was maintained by another team.

    In the migration phase, I rewrote the "Boleto" payment option for Brazilian customers in the new system, handled the integration with a third-party payment services provider through webhooks, and increased test coverage with unit tests.

    I also customized the React front end—enabling a seamless user experience by allowing the customer to make payments with a Boleto barcode quickly.

    I paved the way for another payment option with a different payment service provider for low-credit customers, similar to a subscription model (installments).

    I met with the partner company's director of engineering to agree on a custom-made solution and the design and integration.

  • Data Visualization for Public Student Data

    While maintaining and refactoring a legacy codebase, I created the data visualization functionality for the company's then-main product.

    I used Ruby on Rails and optimized SQL queries to aggregate preprocessed public records of São Paulo students' data and displayed that in different levels of granularity using line plots, histograms, and pie charts with React. Every school period, a background task was executed, and it updated the records.

    The customer (teachers and other education professionals) could then compare different schools on a higher level or see the areas in which a particular class and/or student was struggling and act accordingly.

  • Fan-out Sendgrid Integration

    I rewrote a Python service using Go to improve throughput and handle the increasing load. The service fans out Sendgrid webhook calls to two other email campaign management vendors.

    This project involved coordination with the email marketing analysts and also the vendor's engineering team, as that integration wasn't documented.

    I created the Go service from scratch—changing the internal design to be asynchronous using Goroutines with exponential backoff for failed requests.

    The result was a service that could handle webhook callbacks from email blasts to the entire user base (around ten million at the time). During peak hours, it was scaled to >10 instances, each running about 900 Goroutines concurrently.

    This service enabled the email marketing team to analyze their email campaigns in real-time with confidence that their data was, in fact, correct.

  • Online File Directory (via Toptal)

    I rebuilt the entire file upload feature (both frontend as well as backend).

    The entire UI was rewritten from scratch using React, and I also added the ability to create nested folders.

    I also wrote a drag-n-drop functionality on the desktop, including multiple file dragging.

    Added a new progress bar component with the status of multiple files being uploaded in sequence.


  • Languages

    Ruby, HTML5, TypeScript, Go, Python, SQL, JavaScript, GraphQL, HTML, CSS, SCSS, Elixir, Python 3
  • Frameworks

    Ruby on Rails 4, Ruby on Rails 5, Ruby on Rails (RoR), Redux, Django, Django REST Framework, Bootstrap, Angular, AngularJS
  • Libraries/APIs

    Ruby on Rails API, REST APIs, Sidekiq, React, Redis Queue
  • Tools

    Vim Text Editor, Celery, Postman, Tmux, RabbitMQ, Git
  • Other

    Back-end, Vi, Ruby Performance, Webhook, IT
  • Paradigms

    Test-driven Development (TDD), Agile Software Development, Functional Programming, Concurrent Programming
  • Platforms

    Linux, MacOS, Docker, Amazon Web Services (AWS), AWS Lambda, New Relic
  • Storage

    PostgreSQL, Redis, MySQL, Elasticsearch, Datadog


  • Bachelor's Degree in Information Systems
    2014 - 2017
    FIAP - São Paulo, Brazil


  • edX Honor Code Certificate for The Analytics Edge
    edX Berkeley
  • edX Honor Code Certificate for Scalable Machine Learning
    edX Berkeley
  • edX Honor Code Certificate for Introduction to Big Data with Apache Spark
    JULY 2015 - PRESENT
    edX Berkeley

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