Smart city mobile app: Speeding up time-to-market by 37% with a cross-platform tech stack

Project overview
Imagine a mobile app that combines your city’s parking and EV charging services, public transport tickets, and utility contract management. Now, add a robust marketplace where you can order food delivery and buy local products with a few taps to that very app.
AEINS Business Intelligence GmbH and a German municipal utility operator, Stadtwerken Trier (SWT), joined forces to create this kind of app. Together, they founded Portazon, a startup charged with creating and maintaining a smart city super app for Trier and the region.
As a smart city super app, Portazon would be the go-to place to manage SWT utility contracts and order deliveries from local shops and restaurants. It would also provide an easy way to obtain and access two types of public transport tickets: Deutschlandsemesterticket (Germany Semester Ticket) for students and the €49 DeutschlandTicket (Germany Ticket).
But to turn this super app into a powerful, engaging experience, Portazon needed a reliable partner to ensure the apps remained fast, responsive, and compliant.
Services


Challenges
The project’s key challenges involved speeding up the time to market and minimizing the upfront investment. At the same time, both iOS and Android mobile apps had to perform well and deliver smooth user experiences.
That made cross-platform development a more suitable option than native development. However, it came with its own challenges. Those included ensuring compliance with app store policies, user experience consistency, high performance, and seamless integrations.
Finally, as the app was intended for use in Germany, Portazon needed us to comply with its privacy and data security laws, most notably the GDPR.
Our exhaustive discovery phase revealed our client’s key business needs and technical requirements as follows:
Strategic business needs
01 Speed up time-to-market by at least 20% compared to native mobile app development
02 Reduce upfront development costs by at least 20% compared to native mobile app development
03 Reach a user engagement rate of at least 75% within the first year
04 Minimize maintenance and support costs in the long run
05 Ensure compliance with applicable privacy and data security regulations, including the GDPR
Technical requirements
01 Build iOS and Android smart city mobile apps using a cross-platform tech stack
02 Ensure compliance with App Store’s and Google Play Store’s developer policies and guidelines
03 Implement key features: parking lot and EV charging station lookup and payment; public transport ticket and utility contract access and management; a marketplace for local restaurants and shop
04 Integrate map services to provide a map view of city services, including parking lots and charging stations
05 Maximize code maintainability with a component-based development approach and codebase optimized for fast update deployment
06 Ensure user experience consistent with native mobile apps and operating system features
07 Implement support for credit card, Google Pay, and Apple Pay payments
08 Achieve the application performance index (Apdex) of at least 85 for both mobile apps
09 Secure a task success rate of at least 85% for both mobile apps and minimize time on task
Our cross-platform development expertise will minimize costs while accelerating time-to-market and ensuring top performance and UX.


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Solutions
We opted for Ionic and Angular to build a cross-platform mobile app that provides a consistent UX on iOS and Android devices. Furthermore, Kendo UI, a JavaScript UI library bundle, helped us speed up development and cut costs even further without compromising the quality of the UI/UX experience.
Our attention to user experience and comprehensive testing paid off. Both apps secured an 83% user engagement rate and an 89% task success rate. At the same time, we ensured the apps loaded fast and responded smoothly to user actions, all while achieving an Apdex score of 92.
As a result of our work, Portazon’s Android and iOS mobile apps were fully compliant with applicable privacy and data security laws, as well as app stores’ developer policies. The apps themselves provide a native-like experience while cutting down development costs by 31% and time-to-market by 37%.



Online marketplace for local businesses
Portazon connects Trier residents with local retailers and restaurants via a convenient marketplace. This marketplace allows customers to place orders for food and product delivery at any partner retailer or restaurant. Partner businesses retain full control over pricing, shipping fees and modalities, and listed products.
Besides the traditional range of marketplace features, we implemented a combined order feature. It allows customers to bundle orders from multiple vendors into a single delivery.
The marketplace experience was a proven success among customers. The feature had a higher-than-average engagement rate of 86%.

Convenient payment methods
We integrated both apps with a credit card payment processor, as well as Google Pay on Android devices and Apple Pay on their iOS counterparts. We thoroughly tested these integrations to ensure the payment experience remains frictionless, smooth, and error-free.
Our efforts proved rewarding. The payment process was the most intuitive user flow across the app, and our testers' task success rate reached 96%.

Utility contract management
As a principal backer of Portazon, SWT wanted the app to provide comprehensive contract management features to locals. We helped the company turn its ideas into a fully functional SWT customer center for residents of Trier and the region who use SWT’s gas, electricity, and water services.
With all invoices, discounts, readings, and data adjustments centralized in the app, local residents could finally manage their utility contracts on the go. Thanks to our iterative interface refinements, the customer center saw an engagement rate of 84%.

Ticket access and management
To make the transition to smart city services smoother, Portazon aimed to facilitate access to and use of common public transport tickets via its mobile app. To that end, we integrated support for both the Germany Semester Ticket for students and the €49 Germany Ticket.
Thanks to our extensive testing, adding a ticket to Portazon became a matter of several simple taps. Users can also easily pay for a ticket without leaving the app thanks to our payment integrations.

Parking and EV charging access and payment
Portazon was also conceived as a convenient way to find EV charging stations and municipal parking lots and pay for their services. To make it a reality, we integrated an intuitive map view so that users could easily find the needed charging station or parking lot. Payment integrations, in turn, allow users to pay for parking and charging within the app.
Early user feedback praised a streamlined payment experience and convenient location lookup. Our performance-optimized development approach and thorough testing made user flows faster, eliminating the risk of unnecessary lag or unexpected errors.

City services at a glance
Besides parking lot and charging station lookup, we also added a map view for all city services. Those included free Wi-Fi hotspots, ATMs, carsharing stops, and public transport information (e.g., timetables). Users can browse the map itself or quickly find what they need using a search bar and detailed filters.
Thanks to a fast search and intuitive map view, finding the right city service took early users mere seconds, with the task success rate exceeding 91% on both platforms.
Tech stack
Impact
Our cross-platform mobile app development services helped Portazon reach its target goals, including:
We can have your mobile app up and running fast with a cross-platform tech stack, all while ensuring its high performance and scalability.


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