Leonard Lepadatu, Developer in Constanța, Romania
Leonard is available for hire
Hire Leonard

Leonard Lepadatu

Verified Expert  in Engineering

Software Developer

Constanța, Romania
Toptal Member Since
July 3, 2022

Leonard is a software architect and senior full-stack developer with over 28 years in the software industry. This allows him to quickly understand and translate the client's needs from functional to technical specifications to product design and development. He worked for HP, Groupe HN, Natixis, Airbus Defence and Space, Bayer, Murex, Safebridge, Enel, Airbnb, Boeing, Zurich University, Nati, United Nations, Lennar Corp, etc.


React, D3.js, Snowflake, Dashboard Development, Mapbox, MUI CSS...
Brandwork Studio Ltd
Web Design, Data Visualization, UI Design, Web UI Design, User Interface (UI)...
React, Redux, TypeScript, Full-stack Development, Full-stack, OAuth, APIs...




Preferred Environment

Linux, Docker, Visual Studio Code (VS Code), Full-stack Development, Full-stack, D3.js, React, Node.js, Next.js

The most amazing...

...project that I've architected was MyEnel, which eases the B2B and B2C energy contracting experience for more than two million users monthly.

Work Experience

React Developer

2023 - PRESENT
  • Fixed the logic of the data visualization application running on large screens or resolutions.
  • Tracked and fixed bugs with Jira and Kanban and cross-reviewed code.
  • Implemented data visualization widgets using D3.js and fed them using a back-end Express.js API that caches Snowflake queries.
Technologies: React, D3.js, Snowflake, Dashboard Development, Mapbox, MUI CSS, Amazon Web Services (AWS)

UX/UI and Data Visualization Full-stack Developer

2022 - 2022
Brandwork Studio Ltd
  • Developed a web app for management of the Peoples' Climate Vote for the United Nations and Oxford University.
  • Managed the project using Jira and Bitbucket and deployed it on AWS EC2.
  • Met client expectations with over 400,000 visits every month.
Technologies: Web Design, Data Visualization, UI Design, Web UI Design, User Interface (UI), Responsive Web Design (RWD), TypeScript, User Experience (UX), JavaScript, Amazon Web Services (AWS)

Engineering Manager

2021 - 2022
  • Developed the front end of a management platform for a US company that is used to monitor and analyze live data from the mining fields.
  • Wrote user stories, led scrum meetings and interviews, met stakeholders, tracked incident metrics like MTBF, MTTR, MTTA, and MTTF, and wrote code.
  • Oversaw the deployment process and helped the client organize the testing process to efficiently accomplish the delivery phase and report bugs.
Technologies: React, Redux, TypeScript, Full-stack Development, Full-stack, OAuth, APIs, Architecture, API Architecture, System Architecture Design, Amazon Web Services (AWS)

Senior Front-end Developer

2021 - 2021
  • Developed the platform's front-end used by US mining companies to acknowledge and manage the information from the mining fields' machinery.
  • Developed React components and containers. Solved bugs and tracked them using Scrumban in Jira.
  • Refactored React class components to functional components using React hooks.
Technologies: React, Redux, TypeScript, Full-stack Development, Full-stack, OAuth, API Architecture, System Architecture Design


2019 - 2021
Mile Technology DWC LLC
  • Created the first-in-the-world full flight cabin simulators for DAT Center, including simulator projects: the 777/A330 (EVAC system), a business jet with 6deg of a liberty motion system, and the A320/B737 with 6deg of a liberty motion system.
  • Designed and developed all systems platform architecture (hardware and software): the visuals system for real-time simulation of all cabin windows and the cockpit view as well as FDM model software.
  • Built a module for linking E2M's motion platform host and AB's PLC with Mile Technology's iOS.
  • Implemented a module for recording/playing flight missions, a module for flight analyzing flight scenarios models, an iOS for A320/B737, and a business jet (multiple models);
Technologies: C++, OpenSceneGraph, Architecture, Networking

Software Manager

2018 - 2019
Skye Engineering
  • Developed simulation software for aircraft pilot training for various aircraft companies such as Boeing, CAE, and Airbus.
  • Worked on UPRT, rehosting of advanced instructors operating stations for Boeing 767.
  • Implemented the EET integration on Rediffusion for Boeing 747 using C and C++.
Technologies: Fortran, C++, C

Senior Full-stack Architect

2018 - 2018
Fullscreen Digital SRL
  • Designed and developed two projects: the Enel (MyEnel) platform and a large business marketing platform.
  • Worked on Enel's platform architecture which included building authentication and authorization modules, setting workers for MyEnel to synchronize the web nodes with Enel's ERP through Tibco gateway, and making React components.
  • Created LBM's React components and developed and architected the async Bull queues system; also developed the PWA.
Technologies: React, Redux, Node.js, Sequelize, TypeORM, MariaDB, Node-gyp, MongoDB, Mongoose, TypeScript, Full-stack Development, Full-stack, OAuth, APIs, Architecture, API Architecture, System Architecture Design, Progressive Web Applications (PWA)

Engineering Manager

2016 - 2017
  • Led a small full-stack team for developing international web projects for Airbus Defence and Space, Bayer AG, and Zurich University.
  • Managed a four developers team in agile mode to accomplish all company projects. Migrated all company projects from subversion to Git. Implemented Jira for all company projects.
  • Architected and developed scenario management for an internal project at Airbus Space and Defence.
  • Developed JavaScript modules for Dundas BI at Bayer AG.
  • Created and developed the simulation app game for testing egocentrism in small or large companies' teams at the Psychology Department of Zurich's University.
Technologies: JavaScript, React, MySQL, PHP, TypeScript, Full-stack Development, Full-stack, Architecture, API Architecture, System Architecture Design

Team Leader

2015 - 2016
Group HN
  • Led a software developers team and developed complex web application projects for important clients like Natixis and BP.
  • Integrated Salesforce to the internal human resources platform.
  • Architected and developed Mon Expert: an internal platform for selling proofs of concept.
Technologies: JavaScript, PHP, WebApp, MySQL, Full-stack Development, Full-stack, APIs, Architecture

Enel | MyEnel

React and Node.js full-stack application for Enel, the most essential electricity carrier in Italy and Eastern Europe, developing and integrating the rapid contracting platform in Enel's infrastructure.

I was working as a senior architect with hands-on in the back and front end.

Large Business Marketing

A full-stack marketing platform for Nati's large malls in Europe. Created and managed marketing streams according to the GDPR.

I worked as a hands-on senior full-stack developer and then as a senior architect.

Mon Expert

A full-stack web application for Natixis. The application was created for selling POSs to medicine cabinets in France. The project was based on decision trees built and trained before by an admin metier. Later, a phone operator calls the clients, and their answers lead to a new tree or final leaf, the offer.

I started as a senior full-stack developer, and then I was the engineering manager.

Simulation Application

A psychological game for measuring egocentrism in teams.

I worked alone on this spinoff from Zurich University in the Psychology department. The application was played to major teams like Bayer AG, Porched Group, and Airbus.
2005 - 2010

PhD Degree in Project Management

Free International University of Moldova - Chișinău, Moldova

2005 - 2007

Master's Degree in Banking and Financial Management

Andrei Saguna University - Constanța, Romania


Applied Plotting, Charting, and Data Representation in Python



Big Data Analysis with Scala and Spark



Data Science in Python



Parallel Programming



Python Data Structures



Databases with Python



Using Python to Access Web Data



Technology Entrepreneurialship

Stanford University


Functional Programming Principles in Scala



Model Thinking

University of Michigan


Probabilistic Graphical Models

Stanford University


Machine Learning

Stanford University


React, Node.js, REST APIs, jQuery, D3.js, Beautiful Soup


Sequelize, Mongoose, Git, Auth0, Node-gyp, Sentry, Figma, OpenSceneGraph


Redux, FeathersJS, React Native, WebApp, Tailwind CSS, Bootstrap, Material UI, OAuth 2, MUI CSS, Spark, Next.js


JavaScript, GraphQL, PHP, TypeScript, CSS, CSS2, CSS3, CSS4, HTML, HTML5, Python, C++, Fortran, C, Snowflake


Agile Project Management, Web Architecture, Scrum, Kanban, Microservices, API Architecture, UI Design, Agile, REST, Data Science, Web UI Design, Responsive Web Design (RWD)


Linux, Docker, Visual Studio Code (VS Code), Mapbox, Amazon Web Services (AWS), Google Cloud Platform (GCP)


MariaDB, PostgreSQL, NoSQL, MySQL, MongoDB

Industry Expertise

Web Design


IT Project Management, Fintech, Entrepreneurship, Web Scraping, TypeORM, Full-stack Development, Charts, Full-stack, Front-end, Scrumban, Projects, Open Source, OAuth, Authorization, Authentication, Serverless, Single-page Applications (SPA), APIs, Architecture, System Architecture Design, Data Visualization, Web Applications, SaaS, Back-end, Apollo, Fintech Consultant, Big Data, Large Scale Distributed Systems, Supervised Machine Learning, Machine Learning, Decision Modeling, Models, Probabilistic Graphical Models, Big Data Architecture, Digital Banking, Networking, Progressive Web Applications (PWA), User Interface (UI), User Experience (UX), Dashboard Development

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.


Share your needs

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

Choose your talent

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

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