How do I store my contacts so I can retrieve them after a factory reset? Has anyone used the HTC backup app?

I'm going to factory reset my phone and I want to store my contacts somewhere so I can retrieve them after the reset.

Has anyone done this before?
Aren't your contacts automatically synced with your Google account? Htc one m8 usually has Andorid 4.4 so you should check settings>accounts and check if your google account syncs your contact info automatically. You should double check it by logging to your google account on a computer to see if it's working.

Link to contacts: www.google.com/contacts