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Carlos Eduardo Lenz
Verified Expert in Engineering
Software Developer
Florianópolis - State of Santa Catarina, Brazil
Toptal member since September 12, 2017
Bio
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.
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 years
- JavaScript - 5 years
- REST APIs - 4 years
- Go - 4 years
- ECMAScript (ES6) - 4 years
- React - 4 years
- PostgreSQL - 4 years
- Redis - 2 years
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 (PWAs), 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
Experience
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.
Education
2008 - 2010
Master's Degree in Computer Science
Universidade Federal de Santa Catarina - Florianópolis, Brazil
Skills
Libraries/APIs
React, REST APIs, pytables, Microsoft Foundation Class (MFC) Library, NumPy, PyQt, Microsoft Foundation Classes (MFC)
Tools
Microsoft Exchange, Auth0, OneSignal, Git, GitLab, Figma
Languages
Go, HTML, ECMAScript (ES6), Python, CSS, JavaScript, SQL, Java, GraphQL, TypeScript, PL/pgSQL, Sass
Paradigms
REST, Functional Programming, Concurrent Programming
Platforms
Linux, Visual Studio Code (VS Code), Oracle, Kubernetes, Google Cloud Platform (GCP), Twilio, Mailgun
Frameworks
Svelte, Bulma, OAuth 2, Redux, pgTAP
Storage
IndexedDB, Redis, PostgreSQL
Industry Expertise
Healthcare
Other
FaunaDB, HTTP, Conda, HDF, WITSML, Web Services, Cordova, Tornadoweb, PWA, Progressive Web Applications (PWAs)
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