Gustavo Guimaraes, Developer in Berlin, Germany
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Gustavo Guimaraes

Verified Expert  in Engineering

Software Developer

Berlin, Germany
Toptal Member Since
December 11, 2014

Gustavo is a full-stack web developer. A lifelong learner, he enjoys finding solutions for real-world problems through the use of technology. He is an expert blockchain engineer. His writing has helped hundreds of developers getting into the Ethereum smart contract ecosystem.



Preferred Environment

Linux, MacOS, Atom, Shell, Git

The most amazing...

...profitable piece of software I’ve written is a smart contract that raised USD $20 millions for a client.

Work Experience

Software Engineer

2016 - PRESENT
Freelance Work
  • Created and deployed smart contracts on the Ethereum network where thousands of users interacted with. Built non-fungible tokens as well as decentralized finance dapps.
  • Built large-scale decentralized applications. Managed a team of eight developers to deliver a fast implementation of software features.
  • Hired, coached, and reviewed the performance of eight software engineers in a project which delivered the fast implementation of software features.
Technologies: Test-driven Development (TDD), React, Ethereum, Smart Contracts, Ethereum Smart Contracts, Node.js, Vue, Solidity

Researcher and Full-stack Web Developer

2014 - 2015
Alexander von Humboldt Foundation - German Chancellor Fellowship
  • Built custom posting, upvoting, and comment systems.
  • Created educational platforms where German universities can post their online courses.
  • Used Geocoder to detect user location.
  • Reworked software into a Sinatra application deployed on Heroku.
Technologies: Ember.js, Ruby on Rails (RoR)

Full-stack Web Developer

2014 - 2014
Wizard Development
  • Created and maintained startup products using Ruby on Rails and Ember.js.
  • Assisted with the database schema architecture.
  • Integrated the Github API to receive push notifications of commit activity.
  • Used the native HTML5 video element to play videos.
  • Utilized the HTML5 Video API to create an annotation system for adding notes to cue points in the video, similar to SoundCloud comments.
  • Implemented a testing framework (Rspec and Capybara) in client projects.
  • Built custom posting, upvoting, and comment systems from scratch in Ruby on Rails.
Technologies: Compass, Sass, Ember.js, Ruby on Rails (RoR)

Full-stack Web Developer

2013 - 2014
NYC Web Development Fellowship
  • Applied full-stack web development practices and stacks on projects, including but not limited to: JavaScript, Angular, Ruby, Rails, Sinatra, SQL, databases, system operations, HTML/CSS, and APIs.
  • Collaborated with teams using Agile software development and test-driven development practices.
  • Created a social media social visualization data visualization tool for a NYC-based interior design startup.
Technologies: CSS, HTML, Sass, Angular, SQL, Sinatra, Ruby on Rails (RoR), JavaScript, Ruby


2010 - 2013
Creative Magenta
  • Developed web applications for clients in Chile, Brazil, USA, and Great Britain.
Technologies: HTML, CSS, PHP, JavaScript, Ruby

Open HPI

Massive Open Online Course platform created at the Hasso Plattner Institute in Germany. It allows anywhere in the world to take computer science courses over the internet.

One Month
A revenue data visualization tool. I created the tool and maintained and added new tests to business logic classes.

Neighborgoods Brooklyn

The first of its kind household goods library with a wide range of goods to borrow and convenient options for receiving and returning items.


Sass, Ruby, JavaScript, PHP, CSS, HTML, Solidity, SQL


Sinatra, Ruby on Rails (RoR), AngularJS, Ember.js, Compass, Angular


Atom, Sublime Text 3, GitHub, Vim Text Editor, Git, Shell


Agile Software Development, Test-driven Development (TDD), Behavior-driven Development (BDD), Scrum


Communication, Smart Contracts, Ethereum Smart Contracts


Social APIs, jQuery, Node.js, Vue, React, Chart.js


Linux, Heroku, MacOS, Ethereum, Blockchain


PostgreSQL, Amazon S3 (AWS S3), MySQLi

2006 - 2010

Bachelor's Degree in Liberal Arts (Elective focus in Economics, Politics, Foreign Languages, and Computer Science)

Lawrence University - Appleton, WI, USA


Ethereum Developer

B9 labs

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