Qardl: Digital Business Card Platform

What We Did

• iOS and Android app development
• QR code generation and scanning system
• Subscription management (Apple and Google)
• RESTful API architecture
• ExpressionEngine CMS integration
• OAuth authentication system
• Push notification infrastructure
• Contact export functionality

About the Project

Qardl is a modern solution to an age-old networking problem: the cumbersome business card. We developed a comprehensive digital business card platform that allows professionals to create, customise, and share their contact details instantly via QR codes. The application serves both app users and non-app users, making it accessible to everyone at networking events regardless of whether they've downloaded the app.

Built using a hybrid app development approach with Framework7, the platform delivers native-like performance on both iOS and Android whilst maintaining a single codebase. This meant faster development cycles and consistent user experience across platforms. The app includes sophisticated features like multiple profile management, allowing users to maintain separate business cards for different roles or organisations, and a job matching system where professionals can signal their availability or hiring needs.

We implemented a flexible subscription model through both Apple and Google's payment systems, giving users access to premium features including advanced card customisation and unlimited QR code exports. The backend infrastructure, powered by ExpressionEngine and a custom REST API, handles member account management, card storage, and real-time synchronisation across devices.

The Challenge

The client approached us with a vision to digitise the networking experience, but several technical and user experience challenges needed solving:

• Creating a seamless sharing experience that works for both app users and people who haven't downloaded the app yet
• Building a robust QR code system that could be scanned instantly at busy networking events without connectivity issues
• Designing an intuitive interface that professionals of all technical abilities could use confidently
• Implementing dual subscription systems (Apple and Google) with proper receipt validation and subscription management
• Developing a scalable backend that could handle rapid user growth whilst maintaining performance
• Exporting contact information in standard formats that integrate with existing phone contacts and CRM systems
• Managing multiple user profiles without creating confusion or accidental information sharing

Our Solution

We took an MVP approach to development, launching with core functionality first and then iterating based on user feedback. This allowed the client to enter the market quickly whilst we refined advanced features in subsequent releases.

Cross-Platform Architecture

We selected Framework7 as our development framework, which provided the perfect balance between native performance and development efficiency. This cross-platform strategy allowed us to build simultaneously for iOS and Android, reducing development time by approximately 40% compared to native development whilst still delivering the smooth animations and responsive interactions users expect from modern mobile applications.

QR Code Technology

The QR code system sits at the heart of Qardl's functionality. We implemented a dual-purpose QR code generator that creates both app-specific codes (for instant profile sharing between Qardl users) and universal web links (for sharing with non-users). Each QR code can be customised with the user's branding and exported in multiple formats for use in email signatures, presentation slides, or printed materials. The scanning system includes sophisticated error correction and works reliably even in challenging lighting conditions at events.

Backend Infrastructure

We built a robust REST API using PHP and MySQL that handles all data operations, from user authentication to card sharing analytics. The API integrates with ExpressionEngine CMS, which provides the client with powerful member management capabilities without requiring custom administrative interfaces. This enterprise-grade approach ensures the platform can scale as the user base grows, with proper caching, database optimisation, and API rate limiting built in from the start.

Subscription Management

Implementing dual subscription systems for iOS and Android required careful attention to Apple and Google's respective guidelines. We built a unified subscription service that validates receipts from both platforms, manages subscription states, and handles edge cases like refunds, subscription changes, and lapsed payments. Push notifications keep users informed about subscription renewals and important account events.

Contact Export System

Understanding that users need their contacts to integrate with existing workflows, we implemented export functionality that generates standard vCard (.vcf) files. These files work seamlessly with iOS Contacts, Android Contacts, Outlook, and most CRM systems. Users can export individual contacts or batch export their entire network with a single tap.

Security and Privacy

We implemented OAuth 2.0 for secure authentication, ensuring that user credentials are never stored in plain text. All API communications use SSL encryption, and the system includes role-based access controls to prevent unauthorised access to profile data. Users maintain complete control over which information appears on each profile and who can access it.

The Results

• Successfully launched on both iOS App Store and Google Play Store in 2025
• Created a scalable platform that handles multiple user profiles and unlimited contact storage
• Delivered intuitive QR code sharing that works at networking events without requiring internet connectivity
• Implemented robust subscription management across both major mobile platforms
• Built a flexible backend system that allows the client to manage users and monitor platform health
• Enabled seamless contact export in industry-standard formats for integration with existing systems
• Provided a foundation for future feature development including job matching and advanced networking capabilities

Technical Highlights

• Frontend Framework: Framework7 for hybrid mobile development
• Backend: PHP with MySQL database
• CMS: ExpressionEngine for member management
• API: RESTful architecture with OAuth 2.0 authentication
• Push Notifications: Firebase Cloud Messaging for iOS and Android
• Subscriptions: Apple StoreKit and Google Play Billing integration
• QR Technology: Custom QR code generation with multiple export formats
• Contact Export: vCard (.vcf) generation for universal compatibility

Need a Business or Networking App?

We specialise in building business applications that solve real-world problems for professionals and organisations. Whether you need a mobile app for networking, productivity, or customer engagement, our team can deliver a solution that works reliably on iOS and Android.

Get in touch to discuss your project