If you have important chats, messages or files in Viber, you should back them up. Viber for Android and iPhone have the built-in backup tool to allow users to connect to their Google Drive or iCloud account and backup the Viber chat history there. So when you can restore your Viber conversations to your new phone or get them back when they were deleted accidentally. Except uploading your personal data and chat history to a cloud service, you can also choose to export them to your desktop or laptop using a Viber backup program.
We highly recommend this iPhone Viber data backup & restore which can help you easily back up your Viber chat history (messages, photos, videos and more files) from iPhone to PC and Mac; restore Viber backups from computer to iPhone. You can refer to this tutorial to backup Viber chats from iPhone to Mac for more details. Or refer to the detailed walk-through tutorial video below.