The Casa app is available for both iPhone and Android. However, due to how the mobile key and Pay key are stored on your device and backed up to the cloud, it's not possible to retrieve them from a cloud backup automatically on a different phone when you're switching from iOS to Android or from Android to iOS.
It is easily possible, though, to migrate your key from one OS to the other using QR code backups.
Even if you can't pull the backup from your phone's cloud service, you can still transfer the key by using our QR code export/import feature.
See: QR code backups for mobile key and Pay key for step-by-step instructions on how to do this.
What if I don't have the old device and don't have access to a phone with the same OS?
If you do not have your old device and do not have access to a device with the same OS, then you can recover funds from your vault by initiating a recovery transaction using your hardware device in combination with the Casa Recovery Key.
Another alternative is to get another phone which has the same OS as your old phone. From there, you could log into your Casa app, grab the cloud backup, and export the key using the QR code, or sign your recovery transaction from there. It's okay to be logged in to the same Casa account across multiple phones and platforms.
You will not be able to restore Pay funds without using a phone with the same OS, but you can use the QR code backup.
Can I opt out of using the mobile key altogether?
You can optionally replace the mobile key with a second hardware key for a 3-key vault, though 5-key vaults require the use of the mobile key.