For those using Android devices, you can now backup your WhatsApp messages in Gmail particularly Google Drive App.
Don’t worry about your storage because WhatsApp backups no longer count against your Google Drive storage quota.
Open your WhatsApp in your phone Apps, click on the 3 dots in the top right corner of the screen.
Click on Settings and as shown in screen below.
Click on Chats
Click on "Chat backup" then scroll down to Google Drive settings in order to change or configure your backup frequency.
Click on "Backup to Google Drive" and choose how often you want to backup your messages (frequency).
NOTE: By default "Never" option is selected you can change to backup daily, weekly, monthly or Only when I tap “Backup”.