Bruno Philipe, on mastodon.technology:
Mastonaut news: I’ve recently decided to make Mastonaut open-source. I no longer have the time and energy needed to maintain the app, and it has started to lag in features and functionality when compared to the Mastodon web client and other apps.
The app is now free at the App Store.
Sad it’s not being developed anymore, but for now we have a great free Mastodon client on Mac. Hopefully someone will continue work on it.