Some german institutes and companies provide the Contact Tracing App Corona Warn App.
The swiss company Ubique provides the Contact Tracing App NextStep.
A european non-profit-organization defined a standard for Contact Tracing Apps called Pan-European Privacy-Preserving Proximity Tracing (PEPP-PT), with a lot of serious organizations and experts participating.
Additional source: https://www.watson.ch/digital/schweiz/276492590-forscher-kuendigen-laenderuebergreifende-contact-tracing-app-an (DE)