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Case HSL

A service that moves everyone – the HSL app offers the best means of transport in a single package

Many people use their mobile phones to ride public transport in the Greater Helsinki area – in just a few years, Helsinki Region Transport’s (HSL) mobile app has become one of the most popular apps in Finland. Digia has been involved in the development of the app since autumn 2017 and now serves as HSL’s partner in its development and maintenance.


Helsinki Region Transport (HSL) is a joint local authority that procures public transport services to cover its nine member municipalities. Every year, more than 380 million journeys are made using public transport organised by HSL.

The HSL app has been downloaded more than 1.6 million times, and it has about a million active users. Digia has been involved in developing the app since autumn 2017 and, in June 2019, Digia assumed overall responsibility for the technical development of the app.

What we did

  • mobile services

What we used

  • React Native
  • Node.js
  • GraphQL
  • Microsoft Azure

Digia’s developers play a key role in making the app more customer-oriented. At best, more than 120,000 tickets are sold on the app every day. The fact that the service truly works is really essential for all of us.

Timo Kiiveri, Concept Owner, HSL

Transport services in one app

Transport services in the Helsinki metropolitan area are constantly evolving, and there is also a desire to offer mobile access to new services at a brisk pace. HSL previously offered an app for purchasing mobile tickets, but the HSL app, which was released in June 2018, strives to cover the services that users need more comprehensively. At the moment, the app includes ticket purchases, the Journey Planner, transport announcements and alerts related to routes.

“The principle is that the app provides customers with everything they need to use public transport. We want to provide a complete service in a package that is as easy-to-use, performant and personal as possible. The app is playing an increasingly important role in ticket sales, and it has already become a more popular sales channel for single tickets than the HSL card. The Journey Planner built into the app is also very popular,” says Timo Kiiveri, Concept Owner from HSL.

Digia’s developers are the key to faster development

The HSL app was originally developed in a multivendor environment in line with the principles of agile development. However, HSL wanted to accelerate the development cycle, and it sought to do so by centralising the technical development responsibility with a single partner – Digia.

Digia’s team consists of approximately ten developers with full-stack, QA and DevOps expertise. The app was implemented using the modern React Native, Node.js and GraphQL technologies, which have helped to streamline the app. For example, React Native has enabled apps to be created for the iOS and Android operating systems using 99 per cent of the same codebase, which has accelerated development and led to savings.

“Digia’s developers play a key role in making the app more customer-oriented. At best, more than 120,000 tickets are sold on the app every day. The fact that the service truly works is really essential for all of us. The developers have an important role and responsibility, so they are highly motivated to develop an app that performs even better,” says Kiiveri.

The seamless operation of the service is one of the challenges for the app, and this was part of the rationale for transferring the production environment to Azure. More than 30 per cent of HSL’s ticket sales take place via the app, and this proportion is constantly increasing. Even a short outage could give rise to substantial costs and severe inconvenience for users of the HSL app.  From the perspective of quality control, it is a major job to ensure that all of the versions are functioning correctly when they are updated, as several versions of the app are supported simultaneously.

HSL is also working with Digia on system monitoring: the Digia Iiris operational overview service is provided as a monitoring and recovery service for production environments. The service provides HSL with an operational overview and visibility of the monitored systems, including 24/7 incident management.

Further development to go smarter and more personal

HSL aims to continuously improve the app’s usability, reliability and service offering.

“In the future, we will not only be aiming for a smarter, more personalised app; we want to provide an app that customers can count on to cover the full spectrum of functions and services that customers need in their everyday lives,” says Kiiveri.

The app will enable improvements such as better public transport route planning in general: in the future, with users’ consent, the app will be used to collect anonymised travel data.

More ticket products and new modes of payment coming soon

Ticket products are also under constant development to make them more suitable for customers’ needs. In autumn 2019, public transport users were able to purchase an entirely new type of auto-renewing saver ticket, as well as a 70+ ticket, which provides a discount for customers aged 70 or over between the hours of 9 am and 2 pm.  New ticket products will be introduced in the near future: the HSL commuter benefit, a season ticket for customers aged 15–17, and season tickets for 60, 90 and 360 days. Users have also requested more modes of payment, and the app will soon address this by accepting payments by MobilePay and Pivo.

In addition to these new ticket products and modes of payment, the HSL app will also offer the option of buying adults’ single tickets for the internal public transport services in Tallinn and Tartu in Estonia.

“We see it as important to build a service in which different forms of travel can be easily utilised and combined into uninterrupted travel chains,” says Suvi Rihtniemi, Executive Director of HSL.