Carlos Eduardo Lenz, Developer in Florianópolis - State of Santa Catarina, Brazil
Carlos is available for hire
Hire Carlos

Carlos Eduardo Lenz

Verified Expert  in Engineering

Software Developer

Location
Florianópolis - State of Santa Catarina, Brazil
Toptal Member Since
September 12, 2017

Carlos has over 15 years of experience writing software—including desktop applications, single-page applications, REST APIs, and relational databases. He writes and speaks English fluently and has experience in agile and working in distributed teams. He also has earned a master's degree in distributed systems.

GoReactLinuxPythonSQLJavaScriptREST APIsCSSGitPyQtPostgreSQLPL/pgSQLReduxNumPyRedisIndexedDBProgress 4GL OpenEdge

Portfolio

Ora Oncology, LLC
TypeScript, React, GraphQL, Healthcare, GitLab, Sass, CSS, Auth0, Figma
Studio Fusion Fit
IndexedDB, CSS, FaunaDB, Bulma, JavaScript, Svelte, Auth0...
Venture Tech Group
Redux, CSS, PL/pgSQL, JavaScript, REST APIs, SQL, OneSignal, Mailgun, Cordova...

Experience

SQL - 6 yearsJavaScript - 5 yearsREST APIs - 4 yearsGo - 4 yearsECMAScript (ES6) - 4 yearsReact - 4 yearsPostgreSQL - 4 yearsRedis - 2 years

Availability

Part-time

Preferred Environment

Visual Studio Code (VS Code), Git, Linux

The most amazing...

...project I've done is a P2P network for video-streaming that was developed while earning my master's degree.

Work Experience

Front-end Developer

2021 - 2021
Ora Oncology, LLC
  • Developed a SPA that helps cancer patients to report symptoms, upload, preview, and download files, and communicate with nurses.
  • Developed a SPA that helps nurses manage patients, their symptom reports, communication and file upload, preview, and download.
  • Built the patient onboarding process, from invitation in the nurse app to granting authorization after the patient is correctly logged and has accepted terms in the customer app.
  • Implemented designs from Figma in patient and nurse apps.
  • Tracked and fixed bugs using GitLab as a reporting tool.
  • Worked with a team of front-end and back-end developers, product managers, and designers across sprints to evolve the product.
  • Developed the product to follow HIPAA and protect patients.
Technologies: TypeScript, React, GraphQL, Healthcare, GitLab, Sass, CSS, Auth0, Figma

Full-stack Developer

2020 - 2020
Studio Fusion Fit
  • Developed a PWA for gyms that manages users, instructors, training sessions, schedules, and admin features like reports.
  • Built GraphQL back end with access control and business logic in Fauna DB.
  • Integrated Auth0 login with FaunaDB token generation to produce a serverless solution.
  • Implemented stale-while-revalidate behavior with IndexedDB (client-side) cache.
Technologies: IndexedDB, CSS, FaunaDB, Bulma, JavaScript, Svelte, Auth0, Progressive Web Applications (PWA), PWA

Full-stack Developer

2017 - 2020
Venture Tech Group
  • Developed REST APIs for vehicle service shops (in Go). The system keeps track of service types, resources (tools, staff) usage, and availability before confirming appointments. Developed Opentrack (DealerTrack DMS) synchronization.
  • Developed a SPA for admin users, which manages appointments, resources, customers, and vehicles (in React and Redux). Advanced features include keeping track of integrations and synchronization.
  • Developed a SPA for customers (in React and Redux). Functionality: manage contact info & preferences, vehicles, and personal schedule, with push notifications. Packaged the customer SPA in a Cordova APP.
  • Implemented access control in REST endpoints and across the admin SPA (to display pertinent actions only).
  • Developed, automated, and operated DevOps tools to deploy and upgrade PostgreSQL, Kubernetes infrastructure, SPAs, and Cordova app. Managed the cloud infrastructure of production and development environments (in GCP).
Technologies: Redux, CSS, PL/pgSQL, JavaScript, REST APIs, SQL, OneSignal, Mailgun, Cordova, REST, Auth0, Twilio, Google Cloud Platform (GCP), Kubernetes, Web Services, ECMAScript (ES6), PostgreSQL, React, Go

Full-stack Developer

2015 - 2017
Studio Fusion Fit
  • Created a React SPA for gyms which managed users, instructors, training sessions, and schedules.
  • Developed the backend HTTP API in Go and PostgreSQL.
  • Integrated OAuth2 login through Facebook, Google, and Microsoft.
  • Developed PL/pgSQL functions to manage non-trivial business rules and authorization.
  • Worked part-time before Jan 2017, then full-time until completion in June 2017.
Technologies: JavaScript, REST APIs, SQL, CSS, ECMAScript (ES6), Redux, React, OAuth 2, PL/pgSQL, PostgreSQL, Go

Developer

2010 - 2016
ESSS
  • Developed a client-server application (PWDa) for real-time monitoring of well-drilling (oil & gas industry).
  • Developed sensor data acquisition through WITSML (standard built on top of SOAP).
  • Created an engine for calculations and a rule system for evaluation of operation safety.
  • Defined an optimized DB schema using Oracle’s Index-Organized Tables (because data is “time series”-like). Several SQL queries were also optimized using Oracle features.
  • Built an HTTP API for data access on top of Tornadoweb.
  • Developed a PyQt desktop application accessing data from the server or locally from HDF files.
  • Profiled the Python application.
  • Practiced TDD, CI, Scrum, and later Lean/Kanban.
  • Developed parts of a large software library cooperatively with other developers.
Technologies: Web Services, SQL, WITSML, NumPy, pytables, HDF, Conda, Redis, Oracle, Tornadoweb, PyQt, Python

Developer

2005 - 2007
CITS/Siemens
  • Developed a unified messaging system (convergence of email, fax, and phone).
  • Focused on an MS Exchange integration.
  • Fixed concurrency bugs.
  • Maintained frequent communication with German developers (in English).
Technologies: Microsoft Exchange, Microsoft Foundation Class (MFC) Library, Microsoft Foundation Classes (MFC)

Programmer

2004 - 2004
Datasul Tecnologia (now Totvs)
  • Supported Datasul's developers in Progress 4GL, Java, and XML.
  • Provided support for a Progress 4GL view framework (internal).
  • Supported an enterprise application integration service.
Technologies: Java

SeRViSO: A Selective Retransmission Scheme for Video Streaming in Overlay Networks

https://www.slideshare.net/CarlosEduardoLenz/
SeRViSO is a P2P network for real-time video streaming that handles packet loss selectively, preferring packets that have higher importance for H.264 content.

Worklog

A serverless PWA for personal work logs that supports multiple projects and keeps track of contract and executed hours. It is built using React hooks, GraphQL, and caches everything in the client with IndexedDB.

Languages

Go, HTML, ECMAScript (ES6), Python, CSS, JavaScript, SQL, Java, GraphQL, TypeScript, PL/pgSQL, Sass

Libraries/APIs

React, REST APIs, pytables, Microsoft Foundation Class (MFC) Library, NumPy, PyQt, Microsoft Foundation Classes (MFC)

Paradigms

REST, Functional Programming, Concurrent Programming

Platforms

Linux, Visual Studio Code (VS Code), Oracle, Kubernetes, Google Cloud Platform (GCP), Twilio, Mailgun

Other

FaunaDB, HTTP, Conda, HDF, WITSML, Web Services, Cordova, Tornadoweb, PWA, Progressive Web Applications (PWA)

Frameworks

Svelte, Bulma, OAuth 2, Redux, pgTAP

Tools

Microsoft Exchange, Auth0, OneSignal, Git, GitLab, Figma

Storage

IndexedDB, Redis, PostgreSQL

Industry Expertise

Healthcare

2008 - 2010

Master's Degree in Computer Science

Universidade Federal de Santa Catarina - Florianópolis, Brazil

Collaboration That Works

How to Work with Toptal

Toptal matches you directly with global industry experts from our network in hours—not weeks or months.

1

Share your needs

Discuss your requirements and refine your scope in a call with a Toptal domain expert.
2

Choose your talent

Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.
3

Start your risk-free talent trial

Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.

Top talent is in high demand.

Start hiring