F-Droid is an app store for open source software. You can’t install it from the Google Play store and need to download it from your phone’s browser. Looking through the F-Droid apps is a little like browsing through an eccentric second hand dealer’s wares. There’s a lot of junk but there’s also some great finds.
Voice is absolutely the best audiobook app I’ve ever used. Great UI, great functionality. I use the sleep timer nearly every night. It’s great at remembering where you’re up to. Works with loads of formats, easy to navigate around to different places in a book.
VLC is the best media player, bar none. The desktop version has been around forever. The project has always been free open source software, and always focused on rock solid functionality rather than a fancy UI. I use VLC to play video served through UPnP (gerbera server) on my home network.
AntennaPod ain’t pretty, but it gets the job down without making me feel dead inside. I used Pocket Casts forever, but their advertising model isn’t great and it filters out a lot of content when you’re looking for new pod casts to subscribe to.
Authy is a third party replacement for Google Authenticator. It’s developed by Twilio, which specialises in SMS and Email deliverability, but they’re a significant and reliable tech company. The main advantage over Google Authenticator is that you can sync your credentials between devices. So while Google Authenticator can reside only on a single device, Authy can be used from your phone or desktop or wherever you install it. This also means that you don’t have to re-create all your credentials when you switch phones. 2 factor authentication is great, but as more and more platforms adopt it, getting a new phone and having to re-generate credentials for 3 dozen web sites is a real pain.