Guillaume Ducret, Developer in Challes-les-Eaux, France
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Guillaume Ducret

Verified Expert  in Engineering

Software Developer

Challes-les-Eaux, France
Toptal Member Since
April 17, 2013

Guillaume is an independent consultant with 10 years of experience working with small and large companies globally, focusing on Node.js and JavaScript architecture and development. As a technical lead, he facilitates the adoption of Agile methodologies like Scrum.


Redis, MongoDB, React, Node.js, Android, Flutter, Cloudflare, Svelte
Yaron Lev
Flutter, Front-end Development, Desktop App Development, User Interface (UI)...
Calxis Management Consulting Gmbh [Toptal Teams]
Software Design, Web Development, Architecture, Full-stack, Leadership...




Preferred Environment

Git, MacOS, Visual Studio Code (VS Code)

The most amazing... I've built is a call center application used by 500 agents which processes over 20,000 calls per day.

Work Experience

Software Architect | Full-stack Developer

2015 - PRESENT
  • Led the development of, a SAAS no-code style editor for UI designers.
  • Developed a Flutter package to display map tiles (Sterna—moving map for Flutter).
  • Created a Dart package to sync data from a remote data source. Incremental sync is supported using a Git Repo as a data source (Hive-mirror, one-way sync for Hive DB).
  • Developed a React back end to generate PDFs (React-PDF kit, library to build PDFs using the React API).
  • Worked on both an Android application and an isomorphic web app, Livepeak—a live tracking app for outdoor enthusiasts.
  • Developed an Android application to monitor and control a life support device through a Bluetooth connection.
Technologies: Redis, MongoDB, React, Node.js, Android, Flutter, Cloudflare, Svelte

Senior Front-end Developer

2023 - 2023
Yaron Lev
  • Developed a Flutter app targeting web and desktop.
  • Improved the application state management, which resulted in significant performance improvements.
  • Performed code reviews and introduced best practices.
Technologies: Flutter, Front-end Development, Desktop App Development, User Interface (UI), B2B

Tech Lead

2022 - 2022
Calxis Management Consulting Gmbh [Toptal Teams]
  • Estimated the development effort and helped the product owner to refine his priorities.
  • Defined the project architecture, including live video broadcasting and real-time position tracking.
  • Identified the project's main risks and proposed strategies to mitigate them.
Technologies: Software Design, Web Development, Architecture, Full-stack, Leadership, Scalable Application, Scalable Architecture, Requirements Analysis, Mobile, Video Streaming, Streaming

Lead Developer

2019 - 2022
  • Helped the company to grow from the prototype stage to seed funding.
  • Developed a responsive web application from the ground up.
  • Formalized the development process and onboarded the first employees.
  • Developed a mobile app featuring chat and voice/video calls with Flutter.
Technologies: React, Cloud Firestore, Flutter, Electron, Stripe, Agora, TypeScript

Lead Front-end Developer

2015 - 2018
Performance Immo
  • Developed a web app front end from scratch with React.
  • Developed a React-PDF kit and a React back-end to build PDF documents easily with the React API.
Technologies: Gulp, Webpack, Redux, React

Front-end Developer

2017 - 2017
  • Developed a React Native game dedicated to riding shares.
  • The application connected to the car infotainment system's private wifi endpoint.
  • Developed a Redux-based data synchronization system.
Technologies: React Native, WiFi Integration

Lead Front-end Developer

2015 - 2015
Performance Consumer Groupe
  • Refactored an AngularJS application.
  • Managed two remote developers, defined coding guidelines, and approved pull requests.
  • Provided advice on the implementation of Scrum within the company.
Technologies: Grunt, Bootstrap, Less, CSS3, HTML, AngularJS

Software Consultant

2014 - 2014
The Stack Holder Company
  • Defined the architecture and developed a scalable news monitoring application based on web crawling, content analysis, and entity extraction.
  • Set up a deployment process on AWS, using Git push hooks.
  • Defined and prioritized the product backlog with the product owner.
  • Hired and managed remote freelancers to develop web scrapers.
Technologies: Amazon Web Services (AWS), MySQL, Elasticsearch, Natural Language Toolkit (NLTK), Scrapy, Django, Python

Lead Front-end Developer

2013 - 2014
  • Refactored an AngularJS application.
  • Made the application responsive to work on phones, tablets, and desktops.
  • Implemented a back-office application in AngularJS from the ground up.
  • Worked closely with the product owner to define and prioritize the backlog.
Technologies: Grunt, Karma, Jasmine, Bootstrap, Less, Sass, CSS3, HTML5, AngularJS, CoffeeScript

Full-stack Developer

2012 - 2013
  • Built a social platform inspired by Pinterest, with a focus on user collaboration.
  • Used PhantomJS to improve the SEO of the single-page application.
  • Integrated Google Maps to display location-based search results.
Technologies: Backbone.js, Heroku, Solr, Redis, MongoDB, Node.js, JavaScript

Technical Lead

2010 - 2012
  • Developed a content exchange platform with social features for this Singapore-based startup.
  • Improved productivity and managed business expectations by implementing Scrum methodology within the organization.
  • Managed three cross-functional teams of fifteen individuals, which included such tasks as running daily standup meetings, performing code reviews, and ensuring quality of delivery.
  • Designed and implemented key framework components, including a persistence layer on top of Cassandra and an event infrastructure.
Technologies: Amazon Web Services (AWS), Linux, Apache JMeter, jQuery, RequireJS, Jetty, Spring, Jackson, Jersey, REST, HornetQ, Solr, Cassandra, JavaScript, Java

Software Architect

2008 - 2010
  • Worked as a software architect on a new call center application used by 500 agents and processing over 20,000 phone calls per day for a French pension fund.
  • Wrote technical specifications with UML.
  • Provided expertise on OSGI.
  • Built a technical infrastructure on top of OSGI by integrating frameworks to support clustering, hot deployment, client-server communication, and functional scalability.
  • Deployed a build management infrastructure using Maven 2 and Hudson.
Technologies: Linux, Shell Scripting, IBM Rational ClearCase, Hudson, Apache Maven, Avaya Software, JTAPI, JMX, RMI, Eclipse RCP, Hibernate, JBoss Cache, Apache MINA, Spring, OSGi, Java

Software Engineer

2007 - 2008
  • Designed and developed a messaging web application to facilitate the communication between employees located in two different offices for a tax collection agency in France.
  • Provided expertise on Hibernate and Quartz to solve design issues on a clustered web app.
  • Implemented Web Services using Axis2.
  • Successfully overcame a scalability issue by setting up a load test infrastructure and optimizing SQL statements.
Technologies: Eclipse, CVS, Continuum, Apache Maven, Apache JMeter, PostgreSQL, Apache Axis 2, Hibernate, Quartz, Apache Struts, jQuery, Ajax, CSS, Jakarta Server Pages (JSP), Apache Tomcat, Jakarta EE, JavaScript, Java

Software Engineer

2006 - 2007
  • Designed and developed automated non-regression test tools within the quality assurance department of a French travel software company.
  • Developed a Java layer on top of the C++ central system communication API with JNI.
  • Increased process efficiency by developing a tool to test back-end availability.
Technologies: Eclipse, IBM Rational ClearCase, Microsoft SQL Server, Ant, XSLT, jQuery, JavaScript, Jakarta Server Pages (JSP), JNI, WebLogic, Jakarta EE, Java

Software Engineer

2004 - 2006
  • Developed and tested a business process management web app.
  • Wrote functional test plans and signed off releases.
  • Performed load testing and tuned application server accordingly.
  • Tested database compatibility.
  • Provided second-level support for customers.
  • Wrote how-to and code snippets for developer users.
Technologies: OpenStack, Eclipse, Visual SourceSafe, Oracle, MySQL, BPM, JUnit, JBoss, Jakarta EE, Java

Flight Display
A collection of EFIS (Electronic flight instrument system) components implemented with Flutter. This is a personal project to evaluate Flutter.


Live tracking for your outdoor activities. Livepeak uses your phone's GPS to share your location in real time.

This is a personal project, of which I performed 100% of the designing and programming.


Collaborative aggregation platform. It's always been challenging to discover and follow great content on the web that matches your interest. AyStack relies on a community of users to make it easier.

This is a personal project, of which I performed 100% of the designing and programming.


JavaScript, Java, Kotlin, CSS, XSLT, HTML, CSS3, Less, Python, CoffeeScript, HTML5, Sass, TypeScript


Redux, Spring, OSGi, Hibernate, Flutter, Svelte, Jersey, Jakarta Server Pages (JSP), Apache Struts, Apache Axis 2, Apache MINA, JNI, JUnit, AngularJS, Bootstrap, Django, Scrapy, Jasmine, React Native, Electron


Node.js, RxJS, React, Java RMI, JTAPI, RequireJS, jQuery, Backbone.js, Jackson, Quartz, JMX, Natural Language Toolkit (NLTK), Stripe


Apache Maven, Eclipse IDE, Apache JMeter, Git, Eclipse RCP, Solr, IntelliJ, Jetty, Apache Tomcat, Continuum, CVS, Hudson, IBM Rational ClearCase, Visual SourceSafe, Grunt, Karma, Webpack, Gulp, Agora


Scrum, Test-driven Development (TDD), REST, Scalable Application, Requirements Analysis, Desktop App Development, B2B


Google App Engine, Android, Amazon Web Services (AWS), Heroku, MacOS, Jakarta EE, Eclipse, JBoss, Oracle, OpenStack, Linux, Mobile, Visual Studio Code (VS Code)


Architecture, HornetQ, Ajax, RMI, Avaya Software, Shell Scripting, WebLogic, Ant, BPM, OpenSTA, WiFi Integration, Software Design, Web Development, Full-stack, Leadership, Scalable Architecture, Video Streaming, Streaming, Front-end Development, User Interface (UI), Cloudflare


Elasticsearch, MongoDB, Cassandra, PostgreSQL, JBoss Cache, Microsoft SQL Server, MySQL, Redis, CouchDB, Cloud Firestore

2012 - 2012

SCRUM Master Degree in Agile Methodologies

ODD-E - Singapore

1999 - 2004

Master's Degree in General Education, Software architecture, and Integration of Systems Specialty

EPF - Paris, France