Jonas is available for hire
Hire JonasJonas Schalck
Verified Expert in Engineering
Full-stack Developer
Strasbourg, France
Toptal member since September 28, 2021
Bio
Jonas is a passionate full-stack mobile developer; he loves everything about programming, from researching to scripting, designing, and building solutions for clients. Using his favorite technologies, he single-handedly developed a social networking application that is now in production. Thanks to his work experience as a manager, Jonas demonstrates excellent soft skills, making communicating with him a painless process.
Portfolio
The Forward Thinking Company, LLC.
Dart, Flutter, Firebase, Cloud Firestore, Google Cloud Platform (GCP)...
The Forward Thinking Company, LLC.
Dart, Flutter, Firebase, Cloud Firestore, SVG Animation, SQL, Node.js...
The Forward Thinking Company, LLC.
Dart, Flutter, Firebase, Cloud Firestore, Node.js, Google Cloud Platform (GCP)...
Experience
- Python - 6 years
- Flutter - 4 years
- Firebase - 4 years
- Dart - 4 years
- Django - 3 years
- Kubernetes - 3 years
- Cloud Firestore - 3 years
- Android - 2 years
Availability
Part-time
Preferred Environment
Ubuntu, Android Studio, PyCharm
The most amazing...
...project I've developed is Zappr, a fully functional social network mobile application.
Work Experience
Head of Engineering
2022 - 2023
The Forward Thinking Company, LLC.
- Handled a new scope of work as a team lead since we struggled to find good leadership candidates.
- Took over people management, including recruitment, team building, feedback strategies, and dismissals.
- Created the boards and automation suited to our operational needs on monday.com, the project management tool we were using.
- Oversaw sprints and their contained tickets for the two teams.
- Bootstrapped and coordinated company-wide efforts such as a custom testing framework.
Technologies: Dart, Flutter, Firebase, Cloud Firestore, Google Cloud Platform (GCP), TypeScript, Technical Leadership, Mobile, Software Architecture, Architecture, Cloud, DevOps, QA Testing, Location Services, NoSQL, Unit Testing, Mobile App Development, CTO, Google Maps API, Mobile Development, Google Cloud Functions, CI/CD Pipelines, Google Play Store, Push Notifications
Flutter Team Lead
2022 - 2022
The Forward Thinking Company, LLC.
- Led the complete scope of work, including delivery to the customer, which consisted of creating a logistics tracking app integrating real-time data.
- Architected the data structure and integration solutions.
- Handled meetings with the customer for discovery purposes.
- Defined technical specifications, created and assigned tickets to developers, tracked the project timeline, and handled board communication with the customer.
- Reviewed PRs and supported developers with challenging pieces of code.
- Provided biweekly individual feedback to developers and ensured growth and proper team spirit with adequate team meetings.
Technologies: Dart, Flutter, Firebase, Cloud Firestore, SVG Animation, SQL, Node.js, Google Cloud Platform (GCP), Technical Leadership, Mobile, Software Architecture, Architecture, Cloud, DevOps, QA Testing, Location Services, Cellular, GPS, Google Location API, Mobile Networks, WiFi, NoSQL, Mobile App Development, Google Maps API, Mobile Development, Google Cloud Functions, CI/CD Pipelines, Google Play Store, Push Notifications
Senior Flutter Developer
2022 - 2022
The Forward Thinking Company, LLC.
- Worked as part of the startup's core team and helped define and build the building blocks of the app, including the coding guidelines, data layer, and supporting generic classes.
- Developed and shipped bigger scoped stories that spanned over a few weeks, which included analyzing the specs, refining them by asking the right questions, and understanding the purpose and value for the customer.
- Fixed any assigned bugs, including SEV (severity) 1 tickets.
- Mentored new developers to teach them both guidelines and mindset.
Technologies: Dart, Flutter, Firebase, Cloud Firestore, Node.js, Google Cloud Platform (GCP), Firebase Cloud Functions, Firebase Cloud Messaging (FCM), NoSQL, Google Cloud, Mobile, Full-stack Development, Cloud, Location Services, Cellular, GPS, Google Location API, Mobile Networks, WiFi, Unit Testing, Mobile App Development, Minimum Viable Product (MVP), Google Maps API, Mobile Development, Google Cloud Functions, CI/CD Pipelines, Push Notifications
Lead Full-stack Developer and CTO
2021 - 2022
Navarc
- Redesigned the database architecture completely into a simpler model.
- Refactored the back end from scratch into a cleaner, maintainable project.
- Optimized and managed the infrastructure alone. Along with the two previous measures, this led to a decrease in infrastructure costs of 70%.
- Introduced best practices, including a proper Gitflow, documentation, and test suite.
- Code-reviewed all pull requests and provided thorough follow-up feedback to ensure the growth of team members.
- Guided all feature-related decisions to ensure technical efficiency and optimal UI/UX.
- Created Selenium scripts to download reports that were unavailable through the API.
Technologies: Python, Flask, Google Cloud Platform (GCP), Firebase, BigQuery, PostgreSQL, TypeScript, Devtron, Argo CD, REST APIs, SQLAlchemy, CRM APIs, Google Cloud, API Integration, Technical Leadership, Docker, Back-end, Full-stack Development, APIs, Selenium, Cloud Infrastructure, Software Architecture, Architecture, Cloud, DevOps, Notion, Unit Testing, Pytest, Web Scraping, CTO, Minimum Viable Product (MVP), FastAPI, Data Scraping, Google Cloud Functions, CI/CD Pipelines, Push Notifications
Co-founder and Full-stack Developer
2019 - 2021
Zappr
- Designed the app structure to allow scaling and included all features of a complete social networking application, such as image and video caching and preloading, push notifications, an integrated camera, and a chat.
- Developed and debugged the complete application alone.
- Shipped the application into production on Android and iOS and deployed the back-end containerized apps into a Kubernetes environment.
Technologies: Python, Django, Android, Flutter, NGINX, Kubernetes, Firebase, Dart, Full-stack, WebSockets, REST APIs, Django REST Framework, iOS, Swift, Mobile, Celery, Redis, REST, Back-end, Full-stack Development, Cloud Infrastructure, Kotlin, Cloud, DevOps, Redis Cache, Unit Testing, Pytest, Mobile App Development, Social Media Apps, CTO, Minimum Viable Product (MVP), Mobile Development, Google Play Store, Push Notifications
Area Manager
2017 - 2019
Zalando
- Created KPIs during the ramp-up phase of a new Zalando logistics warehouse.
- Created and implemented processes that improved productivity and quality delivered as well as the co-workers' safety.
- Managed 150 to 200 people, including disciplinary responsibility. The objective was to permanently maintain and improve the co-workers' motivation by performing monthly feedbacks and advancement.
- Planed and coordinated FTEs to optimally achieve the goals and guarantee transparent communication with internal and external partners.
- Created and programed ad-hoc software in Python, JavaScript (used in Google Sheets), and VBA according to my firm's needs.
Technologies: Management, Change Management, Leadership, Team Leadership, Lean Project Management, Lean, Process Management, Python, Python 3, JavaScript, Google Sheets, Google Sheets API, Excel VBA, Web Scraping, Visual Basic for Applications (VBA), Data Scraping, Outlook
Teaching Fellow
2016 - 2016
University of Strasbourg
- Provided lectures in controlling as a teaching fellow at the University of Strasburg for 4th-semester students.
- Created new exercises and tests covering specific topics.
- Assessed mid-term tests and final exams as part of my role.
Technologies: Controlling, University Teaching
Freelance Developer
2015 - 2015
Freelance
- Developed a tailor-made database management software programmed in VBA for a client used by around 200 users.
- Organized meetings with end users in order to define the project specifications. Established an FAQ and step-by-step tutorial covering all functionalities of the application.
- Provided six months warranty (e.g., bug fixing) and end-user training of key users.
Technologies: Excel VBA, Visual Basic for Applications (VBA)
Assistant Project Manager
2014 - 2015
Daimler AG
- Assisted the project manager in his daily tasks during the pre-project phase of the plant's migration towards a new ERP (SAP). Tasks included implementing the SAP project throughout all its essential phases, milestones, workshops, and meetings.
- Took care of financial issues and summarized the expenses for internal reporting purposes.
- Supervised the call for tenders, analyzed various offers to select the ideal service provider, and drafted the project's contract.
- Wrote a thesis which aimed at analyzing the plant's situation in terms of change management, a field in which I made several recommendations.
Technologies: Project Management Office (PMO), Change Management, Visual Basic for Applications (VBA)
PMO Intern
2014 - 2014
Hugo Boss
- Coordinated new orders coming from the Benelux of France autonomously to construct Hugo Boss shops and stores.
- Calculated cost estimations according to benchmarks and assisted cost and invoice control.
- Ordered via SAP and organized transportation of shop components.
- Created cross-departmental tools to automate cost extensive administrative tasks in Excel VBA and more generally solved any Excel-related problem.
Technologies: Project Management Office (PMO), Excel VBA, Visual Basic for Applications (VBA), Outlook
Experience
Zappr
A complete social networking application that was written with Flutter. The API back end is written in Python using the Django framework.
I was the sole developer on the project, which means I had to manage every step of the process, from designing its structure to shipping it into production.
I was the sole developer on the project, which means I had to manage every step of the process, from designing its structure to shipping it into production.
Education
2010 - 2015
Master's Degree in Business Administration
EM Strasbourg Business School - Strasbourg, France
Skills
Libraries/APIs
Django ORM, REST APIs, SQLAlchemy, Google Maps API, Google Location API, Google Sheets API, Node.js
Tools
Android Studio, PyCharm, GitHub, Devtron, BigQuery, Pytest, NGINX, Google Sheets, Firebase Cloud Messaging (FCM), Celery, Notion
Languages
Python, Dart, Excel VBA, Python 3, Kotlin, JavaScript, TypeScript, Visual Basic for Applications (VBA), Java, Swift, SQL
Frameworks
Django, Flutter, Flask, Django REST Framework, Selenium
Paradigms
Change Management, Unit Testing, Mobile Development, Management, REST, DevOps
Platforms
Ubuntu, Google Cloud Platform (GCP), Mobile, Android, Firebase, Kubernetes, iOS, Docker
Storage
PostgreSQL, Cloud Firestore, Redis Cache, NoSQL, Google Cloud, Redis
Other
Leadership, Team Leadership, Lean Project Management, Lean, Full-stack, WebSockets, Mobile App Development, Minimum Viable Product (MVP), Google Cloud Functions, CI/CD Pipelines, Google Play Store, Push Notifications, Process Management, Firebase Cloud Functions, Technical Leadership, Back-end, Software Architecture, Architecture, Cloud, Location Services, Cellular, GPS, Mobile Networks, WiFi, Social Media Apps, CTO, Outlook, Controlling, University Teaching, Project Management Office (PMO), Argo CD, SVG Animation, CRM APIs, API Integration, Full-stack Development, APIs, Cloud Infrastructure, QA Testing, Web Scraping, FastAPI, Data Scraping
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