Koronavilkku is a contact tracing app produced by the Finnish Institute for Health and Welfare (THL) to help you find out whether you may have been exposed to coronavirus. If you have a coronavirus test and are diagnosed as infected, you can use the app to share this anonymously with those you have been in close contact with. Your privacy is strongly protected.

Read more about the app ›

How do I use the app?


Download the free Koronavilkku app from an app store (e.g. Apple App Store and Google Play) to your mobile phone. The app works automatically in the background without affecting phone use or draining the battery.


The phones of Koronavilkku app users send a randomly generated code to each other when they come into close contact. The phone stores anonymous information about the contact.


If you have been close to someone who reports that they have been taken ill, you will receive an alert of potential exposure. If you have been diagnosed with coronavirus, the health service will send you a key code. When you tap this code into the app, you anonymously alert other Koronavilkku app users who have been close to you of potential exposure.

Download application Help to get started

How does the app work?

The phone receives a randomly generated code

The app assigns a random code to each phone. The code contains no information about you or your phone.

Phones swap codes with each other

When close enough to each other, the apps swap codes through a Bluetooth signal. User identity or location is not saved. The app retains the codes for 21 days before automatically deleting them.

When someone reports their infection

When a user reports their infection to the app, the app sends the codes it has collected to a server. If you have been in close contact with a code downloaded to the server, the app will send you an alert of potential exposure.

You receive an alert of potential exposure

If you receive an alert of potential exposure, the app will give you further instructions on what to do. The Koronavilkku app can also be used to make a symptom assessment through the Omaolo health check service.

If you are diagnosed with infection

If you have tested positive for coronavirus, a healthcare professional will give you a key code. When you tap this code into the Koronavilkku app, your app sends the codes it has collected to the server. Anyone you have been in close contact with will then be alerted of potential exposure. Since no personal data or information about whereabouts is sent with the codes, you cannot be linked to any potential infection.

Download application

If you receive an exposure notification, follow these instructions


If you have been near a person who has reported their coronavirus infection via the application, you will receive a notification of potential exposure to your phone. Tap on the notification to open Koronavilkku.


Press the red See instructions button.


You will receive instructions on what to do. You will also receive instructions on how to contact a healthcare provider. Read the instructions and press the Contact button.


Select the municipality. You can contact the healthcare services via the contact methods provided by the municipality, such as via the Omaolo online service or by telephone.


The healthcare services will give you more detailed instructions and evaluate your need for a coronavirus test.

Your privacy is protected

Koronavilkku protects your data and privacy in many ways.

Personal data

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.

How the app works

The app transmits information that the app is working to a server. It also forwards information about whether you have been potentially exposed to infection. All communication between Koronavilkku and the server is encrypted.

The information is stored anonymously on a server in Finland. The server is managed by public administration actors. The information is deleted when no longer required.

Use of the app is voluntary

Use of Koronavilkku is not mandatory and you can stop using the app at any time by deleting it from your phone.