I currently use Authy on my android and my Linux system.
It syncs every new authenticator between my devices but I dont want to trust companies with my security anymore.
I host a nextcloud instance on my homelab. Does anyone know a good FOSS authenticator that can use my nextcloud to sync between Linux and android? Provided that it is available on both of course.
Thanks for any input!
Have you checked out Aegis?
Edit: I missed the Linux requirement, not sure if Aegis works with that in mind
You can use OTPClient on desktop, it can import Aegis encrypted exports.
It's what I do, my TOTP codes originate on the phone because I scan the QR codes with it, but Aegis is set to export a backup each time something changes.
A sync app (FolderSync) runs every night and gets the export to my server, where it gets picked up for offline backups.
I load the latest export in OTPClient only as needed, when I run into a 2fa which is not there.
Both Aegis and OTPClient can be set to ask for password each time you open them.
Keepass supports OTP, and exists on every platform. I use KeepassDX on android.
This is what I used as well (KeePassXC specifically), with Syncthing sharing the .kdbx file across devices.
I’m using this with Nextcloud through WebDAV.
There is a keepass app in Nextcloud to access your keepass database using a web browser (keeweb), keepassXC has a client for Linux, Mac and windows (and all of them work great) and there are many apps for iOS and android.
I use the free version of Strongbox with WebDAV and I haven’t had any problems.
You can just backup the keepass database file and you can also have several databases. Each database has its own password.
I just bitwarden pass manager to store all my 2fa stuff. I just let the company host my account, but if you don't want that then you can self host your own bitwarden server for free. It's very convenient, especially with the autofill on desktop and mobile.
I'm surprised no one has recommended "2FAS" yet. It's the open-source alternative. The app is primarily designed for mobile, but they also offer a browser extension that you could install on Linux if you wanted to. Personally, I always try to keep my 2FA apps unsynchronized with a desktop PC.
Oh, and you can export your secrets at any time. Not like Authy.
andOTP is a good option for Android. It does offer backup capabilities which could be used for syncing. Bitwarden is also good