On June 3rd, 2020, the Greenkeeper app will cease operation (monitoring releases, opening PRs and issues).
you can easily migrate your Greenkeeper account over to Snyk, from today until the 3rd of June 2020, when Greenkeeper will shut down.
We’ll stop Greenkeeper’s operation as an independent service on June 3rd, 2020. For your dependency update needs, we have a brilliant alternative for you: Snyk. The team behind Greenkeeper have spent the past months working with them on next-generation dependency updates as a part of their open-source security product. We invite all of our users to migrate over: Snyk not only has a generous free plan for Open Source repos and small organisations, but also offers dev-friendly security features that Greenkeeper didn’t have. They’re good people, and your repos will be in competent and caring hands.
https://greenkeeper.io/ claims (linked from the readme badge)