I started the Catbird project in 2015 to provide instances of Cats's type classes for types from Twitter Util and Finagle. It's had eleven (human) contributors, and the io.catbird organization currently gets around 20k downloads from Maven Central every month (which is down from a high of 30k per month last summer).
I'm not currently using Finagle or Twitter Util, and the project has fallen a little out of date. It was created before cats-effect existed, and although it includes some cats-effect type class instances, these need attention (see this PR or most of the open issues).
It's licensed under the Apache License, Version 2, adopts the Scala code of conduct, generally follows Typelevel-y principles of pure functional programming, has pretty good test coverage via Discipline, etc. I publish new releases approximately every month, usually within a day or two of the monthly Twitter Util and Finagle releases.
Felix Bruckmeier will be joining the project as another maintainer, so at least I won't be the only one with merging and publishing rights, but in the longer term I think it makes sense for this project to live in the Typelevel organization on GitHub (instead of my personal account), and for its three modules (catbird-util, catbird-effect, and catbird-finagle) to be published to Typelevel coordinates.