Khalil Charfi.
Software Engineer building reliable web, backend, and mobile applications.
Professional Summary
Core Expertise
Engineering Principles
- Prefer simple solutions before introducing abstractions.
- Build maintainable and self-documenting software.
- Optimize after measuring and profiling.
- Write code that other developers can easily understand.
- Design interfaces and systems for long-term evolution.
Career Highlights
- Frankfurt, Germany
- Software Engineer @ CHECK24
- M.Sc. Enterprise Systems Engineering
- IEEE Published Research
- Arabic • English • French • German
- 9+ Years Experience
Programming Languages
Backend Development
Frontend Development
Mobile Development
Databases & Storage
Cloud & Infrastructure
DevOps & Automation
Systems Architecture
Testing & Quality Assurance
Other Technologies
Software Engineer – Fullstack Developer @ CHECK24 Vergleichsportal GmbH (Aug 2022 – Present)
Frankfurt, Germany
- Contributed to the modernization of the travel comparison portal, migrating legacy templates to a decoupled Vue.js frontend system for a better user experience.
- Worked on improving checkout performance and user experience by optimizing frontend rendering and integrating new features into the existing platform.
- Developed and integrated REST APIs to bridge core backend systems, helping eliminate manual data entry steps and reducing client-side overhead.
- Collaborated on database query optimizations and caching strategies, helping improve overall API response times for our active user base.
Software Engineer – Full-Stack Developer @ ASM - All Soft Multimedia (Jan 2019 – Aug 2022)
Sfax, Tunisia
- Contributed to the development of several retail and inventory management applications (Cover 3D Mobile, 3andi, 3andi Partner, ProInventory) used by sales representatives and retail businesses.
- Implemented CouchDB/PouchDB synchronization for Flutter and Ionic mobile apps, enabling sales reps to work reliably in low-connectivity areas.
- Developed backend services in PHP/Laravel to support active mobile users, focusing on query optimizations and stable database structures.
- Integrated Keycloak-based identity and access management (IAM) to support secure multi-tenant role-based access for business clients.
Software Engineer – Mobile Developer (Concurrent Freelance) @ MyBus – Monkey Factory (Mar 2020 – Nov 2020)
Sfax, Tunisia
- Worked on a public transit tracking application using Ionic and Mapbox GL JS, displaying live maps and schedules to commuters.
- Contributed to the data pipeline handling GPS streams, utilizing caching and query structures to improve render times.
- Configured GitLab CI/CD pipelines to automate build and deployment steps, making release cycles more consistent.
Front-End Developer @ Softtodo IT Solutions (May 2018 – Dec 2018)
Sfax, Tunisia
- Developed responsive web interfaces for the IRIDION e-commerce platform using Bootstrap and jQuery, focusing on layouts and usability.
- Built and integrated JSP (Java Server Pages) frontend components and worked with the product team on checkout-flow adjustments.
Android Developer @ ASM - All Soft Multimedia (Mar 2017 – May 2018)
Sfax, Tunisia
- Developed Android companion applications for ERP systems and queue ticketing, integrating them with PHP/Laravel backends.
- Implemented offline-first SQLite synchronization and automated reconciliation logic to reduce data sync discrepancies.
- Integrated Bluetooth printing protocols for queue ticketing hardware to streamline localized checkout processes.
Researcher – THERALYTICS Project @ University of Marburg / Digital Research Centre of Sfax (Oct 2016 – Feb 2017)
Germany & Tunisia
- Contributed to an IoT wearable health monitoring research project, using Spring Boot, MongoDB, and WSO2 Complex Event Processing (CEP) to process ECG stream data.
- Helped develop real-time detection logic for cardiac anomalies under the supervision of academic and clinical advisors.
- Co-authored a peer-reviewed paper in IEEE Transactions on Nanobioscience, collaborating with international research teams.
Cardiac Anomaly Detection System (Theralytics)
Context: Academic IoT wearable health monitoring research project. Challenge: Processing high-frequency ECG streams to detect potential cardiovascular anomalies. Contribution: Developed an IoT data pipeline utilizing Spring Boot, MongoDB, and WSO2 CEP rules. Outcome: Successfully built a research prototype capable of real-time anomaly analysis.
Android Business Automation Suite (ASM)
Context: ERP companion and automated ticket queuing terminal systems for retail locations. Challenge: Resolving queue congestion and checkout synchronization delays during busy hours. Contribution: Implemented offline-first SQLite databases and integrated ESC/POS Bluetooth print commands. Outcome: Streamlined queue management and ticket printing processes at physical checkouts.
Public Transportation App (MyBus)
Context: Public transit navigation and scheduling application. Challenge: Providing live schedules using noisy GPS data streams without overwhelming mobile connections. Contribution: Designed a GraphQL caching pipeline and integrated Mapbox GL JS for map rendering. Outcome: Delivered transit maps and timetables to commuters with reliable timing estimates.
Thesis: Complex Event Processing for Cardiac Anomaly Detection (published IEEE, 2017). Focused on designing and building large-scale software systems.
Gained a strong foundation in algorithms, data structures, and software development principles.
CEP4HFP: Complex Event Processing for Heart Failure Prediction
Afef Mdhaffar, Ismael Bouassida Rodriguez, Khalil Charfi, Leila Abid, and Bernd Freisleben
IEEE Transactions on Nanobioscience, Vol. 16, No. 8 | December 2017
Get in Touch
If you’d like to discuss a role, collaborate on a project, or simply talk about software engineering, I’d be happy to hear from you.