How the app works


How the Jersey COVID Alert app works

COVID Alert is a free app for your mobile phone. It doesn’t use any personal information and will help us to protect each other by slowing the spread of COVID-19.

The app will alert you if it detects that you have been in close proximity with another app user who has recently discovered that they have COVID-19.



The app uses Bluetooth to exchange Random IDs with other Jersey COVID Alert app users nearby – even when the app is closed and your phone is locked. The Random IDs change regularly and cannot be used to identify you, your location, or others you are with.

When 2 phones exchange Random IDs, the app also stores the approximate distance between the two phones and the length of time your phone was near the other user’s phone.

Checking for exposures

Several times a day, the app will check the Random IDs generated by your phone against the list of Random IDs from people who have COVID-19. Only people who have a confirmed case of COVID-19 can choose to share their Random IDs to alert others that they may be at risk.

Match Search


If you‘ve been tested and advised that you have COVID-19 the Jersey Contact Tracing Team will guide you through the process of uploading your Random IDs. You can thenalert others who have been in proximity to you anonymously, if you choose to do so.


Technical documents

For full details about how your device handles Random IDs and checks for exposures, read the documentation on or

Full details about how the app works are published on our GitHub site.

Documentation on  Github

Phone call

Exposure Alerts

If you've been near someone who has COVID-19 for long enough to put you at risk, the app will notify you with an in-app notification called an exposure alert. The exposure alert is only visible to you, on your device, and will be automatically deleted after 14 days. 

Learn more about Exposure Alerts


The app is just one part of Jersey’s coronavirus response. Using the app will help to contain the virus and keep our community safe. If you feel unwell you should contact the Coronavirus Helpline on +44 (0)1534 445566, or your GP, and follow the Jersey Government public health advice.


Download the app

  1. Download the app from your usual app store
  2. Decide settings and permissions
  3. Play your part in slowing the spread of coronavirus and helping to protect our community