Simon Corcos, Developer in Montreal, QC, Canada
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Simon Corcos

Verified Expert  in Engineering

System Architecture Developer

Montreal, QC, Canada
Toptal Member Since
March 20, 2020

An expert in web, mobile, back end, and AI system architecture, Simon is truly a well-rounded full-stack engineer. Passionate about healthcare and data engineering, his ten years of experience in the field allow him to work efficiently and deliver high-quality code. He is the chief technology officer (CTO) at HOP TECH; Simon is responsible for building a digital health platform that leverages the power of AI and IoT to help autistic people, fight COVID-19, prevent diabetes, and more.


React, Next.js, Vercel, Python, PostgreSQL, Node.js, Architecture, Cloud
Barefoot Surf
WordPress, React Native, Buddy
Milliman, Inc. -- Employee Benefits Admin Practice
Xamarin, Scrum, iOS, Android, Azure, Cloud, .NET




Preferred Environment

Google Docs, G Suite, Visual Studio, JetBrains, GitLab, Linux, Windows

The most amazing...

...system I've built is a digital therapeutics platform that leverages the power of AI and IoT wearables to better understand the neurology of autistic people.

Work Experience

Lead Full-stack Developer

2023 - PRESENT
  • Used React to develop the front end of a modern, opinionated BI tool to track KPIs of businesses that use different SaaS to power their operations.
  • Architected and built an integration engine for over 30 SaaS products.
  • Developed the back end of the platform using Next.js and Node.js.
Technologies: React, Next.js, Vercel, Python, PostgreSQL, Node.js, Architecture, Cloud

Fractional CTO

2021 - PRESENT
Barefoot Surf
  • Acted as fractional CTO. Provided technical expertise and advice on software development and software stack.
  • Developed, customized, and maintained their React Native app that teaches people how to surf. One of the most notable tasks was developing a video player plugin for their app.
  • Maintained and customized the WordPress site for their e-learning platform.
Technologies: WordPress, React Native, Buddy

Expert Xamarin Developer

2020 - PRESENT
Milliman, Inc. -- Employee Benefits Admin Practice
  • Developed and maintained a Xamarin iOS and Android app that wraps a web browser, adds authentication, and provides additional options.
  • Developed high-functionality custom renderers for the Android and iOS WebView with enhanced cookie management, file download, and tab management.
  • Revamped the app's UI and UX to match the client's website design.
  • Completed over 50 new features and bug fixes per year on a 10 h/week contract.
Technologies: Xamarin, Scrum, iOS, Android, Azure, Cloud, .NET

Chief Technology Officer (CTO)

2016 - PRESENT
  • Managed a team of eight developers and interacted with stakeholders daily to design and build a system that uses data to help autistic people and their caregivers.
  • Created a cross-platform mobile app displaying a remote-controlled avatar over WebSockets and Bluetooth. The 3D animated avatar can be a fully personalized character with a voice and outfit for each user.
  • Developed and maintained Angular web applications for dashboarding, content management, and data exploration. Optimized application performance to display the millions of collected data with wearable devices.
  • Built and designed a cross-platform app that collects sensitive health-related data from a smartwatch and combines it with the user's profile and history to predict current anxiety levels and autistic meltdowns.
  • Implemented OAuth2 and OpenID authentication for both mobile and web, ABAC authorization, and the complete client and server logging system on the Node.js back end. Secured all communications using HTTPS.
Technologies: System Architecture, Software Architecture, iOS SceneKit, MySQL, MongoDB, Visual Studio App Center, Android, iOS, OpenID, Bluetooth, OAuth 2, ABAC, PostgreSQL, Node.js, Xamarin, Angular, Leadership, CTO, Architecture, Cloud, .NET, Tailwind CSS

C# Developer

2023 - 2023
Tahoe Donner Assocation
  • Developed a Xamarin Android binding library around the Square SDK for Android.
  • Made an exact replica of the Square SDK Android sample application in Xamarin Android.
  • Provided documentation on integrating the binding library for the Square SDK into the client's application.
  • Created a Gradle script to download all the dependency files (AAR and JAR) for any Android package.
Technologies: C#, Gradle, Xamarin, Android, Square, .NET

CTO | Solutions Architect

2022 - 2022
  • Designed the architecture of a modern HR back-office system, accounting for diverse stakeholder needs, various user profiles, SaaS integrations, and extensive requirements.
  • Wrote a comprehensive technical vision document detailing the system's architecture.
  • Negotiated with vendors to secure the best pricing for solutions.
Technologies: Back-office System Development, CTO, Architecture, Cloud

Software Back-end Architect

2020 - 2020
Soulmate LLC
  • Designed the back-end architecture for a dating app (like Hinge or Tinder) that allows members to filter the suggested profiles with a variety of parameters like geolocation (e.g., members within 50km of me), height, age range, etc.
  • Reengineered the existing back end to overcome the limitations of Google Cloud Firestore for queries with a scalable Node.js/Postgres set of services that run on Google Cloud Platform.
  • Provided structure to the team's project management process by setting up in a few hours a project management tool (Open Project) and introduced them to the Agile methodology, user stories, and story point estimations.
  • Provided cost estimates for the back-end infrastructure on Google Cloud and Firebase that covered usage by 1 thousand, 100 thousand, and 1 million users.
Technologies: System Architecture, Node.js, Cost Estimation, Docker, Cloud Firestore, Software Architecture, Google Cloud Platform (GCP), PostgreSQL, Architecture, Cloud

Software Architect

2020 - 2020
Creative Advanced Technologies (via Toptal)
  • Performed requirements elicitation and research to design the architecture and lead a team of developers responsible for the development of a COVID-19 contact tracing application for an entire country in the Middle East (30 million users).
  • Came up with clever solutions to complex problems such as distributing new data every hour to millions of active users while avoiding peak loads or keeping users anonymous while still allowing them to access their COVID-19 test results with the app.
  • Delivered the high-level architectural design of the entire platform, including a vision document, a high-level system diagram, the user stories, and the initial mobile application's UI prototype.
  • Designed key low-level architectural components of the platform, delivering an in-depth architectural overview document, the mobile application architecture diagram, several sequence diagrams, and the system's data structures.
  • Produced job descriptions for the rest of the development team, including back-end developers, iOS and Android developers, and DevOps engineers. Also helped the client screen the candidates during the interview process.
Technologies: UML, Google Cloud Platform (GCP), Android, iOS, Angular, CTO, Architecture, Cloud

ERP Customization Specialist

2015 - 2016
GURUS Solutions
  • Wrote scripts for users of the ERP to query databases, perform data validation, and implemented custom business flows. We used unit testing, acceptance testing, and peer reviews for quality assurance.
  • Spoke directly to the clients to document their needs and figure out how NetSuite could be configured and customized to fulfill those needs.
  • Collaborated with the lead developers to improve and document the development process.
Technologies: SuiteScript 1, JavaScript, NetSuite

Web Developer

2014 - 2015
SOS Cuisine
  • Developed a recipe recommendation algorithm that ultimately used caching and database optimizations to improve performance.
  • Revamped the user profile page, making it responsive, with a cleaner UI and added a “recommended recipes” widget that I created.
  • Tested front-end and back-end components using JavaScript.
Technologies: Amazon Web Services (AWS), Bootstrap, CSS, Less, JavaScript, Doctrine, Symphony, MySQL, PHP

Analytics Software Developer

2013 - 2014
DJL Construction
  • Designed and implemented the system's new architecture.
  • Developed software that could analyze and transform data retrieved from different types of sensors used in cement factories and produce one-pager reports for management.
  • Created an app that could run on Windows 95 and be operated by factory workers to extract the data recorded by cement factory sensors.
Technologies: VMware, MinGW, C, Microsoft Word, Visual Basic for Applications (VBA), Microsoft Access, VB.NET, .NET

Wearable Data Collection App | Xamarin

This mobile app continuously monitors data collected by a clinical-grade wearable (i.e. heart rate, skin temp, accelerometer, and more) and allows the user to mark events at a specific time. The user is informed of his current physiological state through beautiful dashboards and an intuitive UI. The main purpose of the app is to track the health and behavior of subjects in clinical trials.
Built using Xamarin, Angular, Node.js, Bluetooth, and MySQL.

Avatar App for People with Autism | Xamarin

A cross-platform mobile application that displays a customizable 3D animated avatar that interacts with children with autism. The avatar is remote-controlled by a healthcare professional (e.g. therapist) or a caregiver through the same app on a different device. It has shown unprecedented results when used to support autistic kids in their learning activities.
Built using Xamarin, Node.js, iOS SceneKit, WebSockets. It runs on iOS and Android.

MMS Foundation Website | WordPress
I built and maintain the website of the Healthy Mothers of the World Foundation as a volunteer. I am in charge of the foundation's IT department. The website has a beautiful UI and allows visitors to donate via Paypal.
Built using PHP, WordPress, CPanel, GoDaddy, and Paypal.

Contact Tracing App | Architectural Design
The complete architectural design of a COVID-19 contact tracing app based on the Exposure Notifications API developed by Apple and Google. The app is designed to be used by more than 25M users and the back end can be deployed on Google Cloud Platform or On-Prem.

Covid-19 Population Questionnaire | Angular

An Angular 9 web application for health authorities that allows them to survey the country's population with daily questionnaires about the citizen's physical and mental well-being. Very similar to but with conditional questionnaire flows that remember the user if they visit the website with the same device. This app also allowed admins to visualize the data on a map powered by

3D Models Management App | Angular

An Angular front end served by a Node.js back end used to upload, visualize and share 3D models. The app uses Three.js and custom Angular components to display 3D animated characters. The characters can be uploaded by 3D designers and shared with the ASD community to be used as reinforcers in tasks such as homework or learning how to dress.

HOP-Child Technologies Website | WordPress

A WordPress landing page for the startup HOP-Child Technologies. The website presents the company's mission and a contact form protected by a captcha that allows visitors to communicate with the company's sales team.

Video Labeling App | AngularJS

This AngularJS app served by a Node.js back end is used by clinical trial coordinators and researchers. It allows them to label a timeline with custom events. The timeline can be aligned with a video and other data collected during their studies. This tool is very useful when researchers collect physiological data such as heart rate and want to find the correlation with events triggered during the trials.

Criminal Attorney Office Website | WordPress

I was hired to create a WordPress website for a criminal attorney's office. The website looks great and has improved the number of clients they get every month, most of them complimenting the lawyers about the website's visual appearance. Complete with multilingual content, SEO, maps integration, and more. It took about 35 hours to complete.
2011 - 2016

Bachelor's Degree in Software Engineering

(ETS) École De Technologie Supérieure - Montreal, Canada


Certified Node.js Application Developer

OpenJs Foundation


Node.js, Chai, REST APIs, jQuery, React, Protobuf,, OpenID, Doctrine


Visual Studio App Center, GitLab, JetBrains, Visual Studio, G Suite, Google Docs, Microsoft Access, Microsoft Word, MinGW, VMware, GitLab CI/CD, Gradle


Express.js, .NET, Angular, Jasmine, Next.js, OAuth 2, iOS SceneKit, Apache Spark, ASP.NET, Bootstrap, Tailwind CSS, React Native


Google Cloud Platform (GCP), Xamarin, Android, iOS, Docker, Windows, Linux, Amazon Web Services (AWS), WordPress, Azure, Vercel, Buddy


UML, C#, JavaScript, SQL, XAML, HTML5, C#.NET, TypeScript, HTML, Python, XML, CSS, CSS3, Kotlin, SuiteScript 1, Less, VB.NET, Visual Basic for Applications (VBA), C, PHP, R, Java, YAML


MySQL, PostgreSQL, MongoDB, NoSQL, Cloud Firestore, Redis


Test-driven Development (TDD), Behavior-driven Development (BDD), MEAN Stack, RESTful Development, Testing, REST, ABAC, E2E Testing, Continuous Deployment, Continuous Integration (CI), Scrum

Industry Expertise



Back-end, Mobile Apps, CTO, Architecture, Technical Leadership, Software Architecture, System Design, System Architecture, Technical Documentation, APIs, Cloud, Dash, Cost Estimation, Bluetooth, Symphony, Data-level Security, NetSuite, Leadership, Software Engineering, Square, Back-office System Development

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