João Sampaio

Email: // Website: // Location: Braga, Portugal
Latest revision of this resume: // This revision: 2023.04.15


Senior Backend Engineer with over ten years of experience solving real-world problems effectively through technology, making a lasting impact on customers' lives, leading multi-disciplinary teams to achieve their goals, developing quality applications in complex domains, and shipping robust software to production in varied industries. Very detail-oriented, hands-on, and passionate about technology. Mutually exclusive, completely exhaustive modus operandi. Avid student for life. Read more on my website.

Detailed Professional Experience

Close Remote
Senior Backend Engineer August 2019 to present

Close is an all-in-one CRM that eliminates manual data entry and focuses on results-oriented communication.

  • Led multi-disciplinary teams comprised of product managers, designers, and backend and frontend software engineers to implement and deliver complex projects with ambitious goals;
  • Led technical projects, conducting the effort through the various phases of a successful software project:
    • Preliminary exploratory and investigative work;
    • Definition of which technologies to use;
    • Planning of the development phases and estimating required engineering effort;
    • Orchestration of the development effort;
    • Preparing for the phases of internal, private, and public beta testing;
    • And, finally, delivering the project to production.
  • Implemented new design patterns and established new standards at both the application and the infrastructure levels;
  • Implemented improvements to productivity tools and the local development environment used by the entire engineering team;
  • Prioritized and addressed technical debt in a complex codebase with multiple other teams working on often competing tasks;
  • Took on-call shifts as first responder engineer for production outages;
  • Took support escalations shifts as first responder engineer for issues raised by customers;
  • Mentored new software engineers on how the engineering culture of the company works and how the team develops and delivers software;
  • Participated in discussions and decisions about defining which new features to develop for the product;
  • Assisted in hiring new engineers by screening resumes of qualified candidates;
  • Examples of projects I participated in include OpenTelemetry implementation for modern observability capabilities; integration with Stripe for billing; integration with Twilio for calling and SMS capabilities; integration with for analytics metrics; development of an internal tool to orchestrate complex trees of asynchronous tasks; and others.

Technologies used: Python, Flask, SQLAlchemy, MongoEngine, unit and integration tests, asynchronous task queues, PostgreSQL, MongoDB, Redis, AWS, Docker, Kubernetes, Git, CircleCI, GitHub Actions.

AlayaCare Full-time, Montreal, Canada
Software Engineer May 2018 to April 2019

AlayaCare is a provider of revolutionary cloud-based home healthcare software. With an end-to-end solution spanning clinical documentation, back office functionality, client and family portal, remote patient monitoring, and mobile care worker functionality, AlayaCare offers a platform for home care agencies to propel towards innovation and home care of the future.

  • Planned and executed the migration of features from the legacy monolithic codebase in PHP and Symfony to the more modern and innovative micro-services-oriented codebase in Python and Flask;
  • Worked on challenging projects to implement new features as an individual contributor;
  • Assisted senior developers and technical leads in grooming and overcoming challenging tasks;
  • Prioritized and addressed technical debt in a complex codebase with multiple other teams working on often competing tasks;
  • Fixed bugs in several parts of the product, with varying degrees of complexity, as an individual contributor;
  • Participated in discussions about the infrastructure and architecture of the platform;
  • Refactored the integration tests architecture and infrastructure to provide a more robust platform. The engineering team could implement fast and reliable tests to assert the quality of each release.

Technologies used: Python, Flask, SQLAlchemy, unit and integration tests, Selenium, PostgreSQL, MySQL, AWS, Docker, JavaScript, Vue.js, Git, JIRA.

AdRoll Full-time, Remote
Software Engineer April 2017 to April 2018

AdRoll is one of the biggest ad platforms in the world, mainly focused on small and medium businesses, but it also has products and services for big enterprises. It optimizes its customers' ad investments based on a budget and strategies of retargeting, prospecting, and email marketing, giving a high return on investment in a short timeframe.

  • Implemented new real-time big data processing topologies using Hadoop, processing massive amounts of data received daily, in a constant stream, from our customers and the customers of our customers;
  • Worked with a team of engineers to implement a new interface to better assist new customers in quickly ramping up their use of the platform, efficiently accelerating the ROI on their ads;
  • Participated in discussions about infrastructure, architecture, and design of the platform;
  • Assisted senior developers and technical leads in grooming and overcoming challenging tasks.

Technologies used: Python, Flask, SQLAlchemy, Luigi, Java, Hadoop, HDFS, PostgreSQL, DynamoDB, AWS, Docker, JavaScript, React.js, Bootstrap, Git, HighCharts, JIRA.

Trounceflow Full-time and freelance contractor, Remote
Software Engineer October 2016 to November 2017

Trounceflow uses Python scrapers as automated background processes to find and analyze massive financial data from various websites and APIs. The data is plotted in charts to provide insights to customers, allowing them to make critical financial decisions faster in the super competitive financial market.

  • Helped build the platform from scratch to the acquisition of the first customers;
  • Orchestrated the discussions about infrastructure, architecture, and design of the platform;
  • Planned and orchestrated the work of other engineers, leading a small team of junior engineers to build the platform from scratch;
  • Led the team to create a system that finds and scrapes massive amounts of financial data from various web pages and APIs;
  • Led the team to build a data pipeline system that ingested the data from the scrapers, persisted the data in a structured database format, and generated the graphs that the customers ultimately used.

Technologies used: Python, Django, Django REST Framework, Celery, RabbitMQ, Redis, PostgreSQL, Javascript, jQuery, Bootstrap, Heroku, AWS, HighCharts, Git, JIRA.

Freelancer Full-time, Remote
January 2008 to October 2016

Worked with various clients delivering from simple landing pages to complex web applications based on distributed systems, asynchronous workers, databases, caches, etc. All projects were done in Python and Django, with usability and scalability in mind.

Technologies used: Python, Django, Django REST Framework, PostgreSQL, unit and integration testing, Celery, RabbitMQ, Redis, Memcached, Javascript, jQuery, Ember.js, Bootstrap, Heroku, Docker, AWS, Git.

Async Open Source Part-time, São Carlos, SP, Brazil
Software Engineering Intern July 2012 to October 2013

Async develops Stoq, an ERP system for small and medium-sized companies that includes point of sales software, warehouse management, sales and staff reports, a CRM, and more.

  • Developed a desktop application in Python with PyGTK, developing new features, fixing bugs, and writing automated tests, following the directions of senior engineers;
  • Assisted senior developers and technical leads in grooming and overcoming challenging tasks;
  • Started the development of a web-based interface for Stoq;
  • Developed a strategy to migrate users from desktop to cloud-based web applications.

Technologies used: Python, Django, SQLAlchemy, unit and integration testing, PyGTK, OpenVPN, Git, Bazaar, Bugzilla.


Universidade Federal de São Carlos São Carlos, SP, Brazil
Computer Engineering July 2014