Koronavilkku Finnish COVID-19 exposure tracking app

Finnish corona-virus tracing app is named Koronavilkku. The Koronavilkku smartphone app is published to help break infection chains.
Users in Finland can download Koronavilkku to a smart phone (iOS or Android) free of charge from the most popular app stores and the app can be instantaneously downloaded via the links on the koronavilkku.fi website. Koronavilkku has been published in Finnish and Swedish (English version is planned).

The Koronavilkku app will allow people to participate in preventing the spread of the virus. Through the app, people exposed to the virus can be reached and infection chains can be stopped faster.


“The Koronavilkku mobile app is part of the Government’s test, trace, isolate and treat strategy. The app makes it more efficient to reach people exposed to the virus and refer them to treatment. This way, infection chains can also be broken more efficiently”, says Kirsi Varhila, Permanent Secretary of the Ministry of Social Affairs and Health.

The use of Koronavilkku is voluntary, but the more people download it, the more helpful it will be. Now 1.7 million people have loaded Koronavilkku app, which means that coverage is 30% of people in Finland. The app has already sent out many alarms, including Finnish prime minister got alarm with Koronavilkku and she locked herself into the prime minister home for self quarantine.

Budget for app was 6 million Euro (around one million used at the moment). The app development itself cost 147 000 Euro.

Koronavilkku has been designed with security in mind. Koronavilkku does not store your name, date of birth or contact information. It cannot identify you or the people you come into contact with. The app does not collect information about where you are. The app works using regularly changing and randomly generated codes. Users of the app cannot be directly identified from these codes. All communication between Koronavilkku and the server is encrypted. A Finnish known hacker Benjamin Särkkä was suspicious in the spring on all COVID-19 tracing apps, but now has changed the view so that he does now see Koronavikku as serious security risk and recommends installing this app.

Koronavilkku is open source software. License is EUPL-1.2 (European Union Public Licence). Any interest to look at COVID-19 exposure tracking app source code? The source code for the Finnish COVID-19 exposure tracking app(s) is now public at https://www.solita.fi/thl-ja-solita-julkaisivat-koronavilkun-lahdekoodin/

Android app: https://github.com/THLfi/koronavilkku-android
iOS app: https://github.com/THLfi/koronavilkku-ios
Backend system: https://github.com/THLfi/koronavilkku-backend

The COVID-19 exposure notifications Android and iOS app for the Finnish Institute for Health and Welfare (THL) uses Exposure Notifications API which is a joint effort between Apple and Google to provide the core functionality for building iOS and Android apps to notify users of possible exposure to confirmed COVID-19 cases. Bluetooth functionality includes all broadcasts and scans for BLE beacons, along with local database storage.

The backend uses Java 11 and PostgreSQL 12.


  1. Tomi Engdahl says:

    Tältä näyttää hartaasti odotettu koronasovellus Koronavilkku – tavoitteena miljoona suomalaista käyttäjää
    Eniten hyötyä sovelluksesta on tiheästi asutuilla kaupunkialueilla ja muun muassa julkisessa liikenteessä.


  2. Tomi Engdahl says:

    Tämän takia paha bluetooth-aukko ei koske Koronavilkkua Itse pidän
    huoletta päällä
    Jopa miljardeja laitteita koskeva bluetooth-haavoittuvuus nimeltä
    Blesa ei vaikuta mitenkään Koronavilkkuun, vaikka se nojaakin
    ongelmalliseksi todettuun bluetooth low energy (ble) -toimintoon.
    Asiasta kertoo Koronavilkun toteuttaneen Solitan
    teknologia-asiantuntija Sami Köykkä Twitterissä. Koronavilkun käyttö
    on turvallista, koska se ei käytä haavoittuvuuden hyödyntämiseen
    tarvittavaa toimintoa.

  3. Tomi Engdahl says:

    Your smartphone may be able to guess whether you’ve been exposed to the COVID-19 virus, but will it invade your privacy while doing so?

    Contact Tracing Apps Struggle to Be Both Effective and Private


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