Stefan started thinking about Arq back in early 2009 because he wanted an easy-to-use backup program but couldn't find one that worked well. Stefan liked Time Machine and even bought a Time Capsule so he wouldn't have to remember to plug in an external hard drive. But it still only backed up when he was at home near the Time Capsule, and if his house burned down or someone stole his computer and Time Capsule his stuff would be gone. He wanted online backup.
He tried Mozy, Carbonite and Backblaze. They all offered "unlimited" size backup for a fixed fee, but the "unlimited" service had limits. He couldn't back up a network drive, for example. He couldn't keep backups of external drives reliably -- some services promised to delete backups of external drives that haven't been connected for 30 days, even failed external drives.
Amazon S3 seemed like a great place for his backup data. It's backed by the power of a large, profitable, public company. It offers clear durability and availability numbers and replication to multiple data centers. And it wasn't an "unlimited" type of offering, so they didn't add constraints to minimize the amount of backup data he had.
Backing up to S3 felt like real backup, but there wasn't any great software to do it.
Stefan had been working on a project that used Amazon S3 for storage, and stored its stuff as a content-addressable storage (CAS) system, written in Java. He decided to rewrite those bits in Objective-C. Then he added logic to correctly back up all Mac-specific metadata, plus strong encryption, plus a simple but powerful Mac UI. That became Arq.
It turns out lots of people were looking for something similar, and through word of mouth Arq has become very popular among Mac users. Since then we've added a lot more storage options besides Amazon S3, plus a Windows version of Arq.
Twelve years on, we're still improving Arq Backup.
Arq users were comfortable setting up the app and connecting it to their favorite cloud storage account, and they recommended Arq to their friends. But for friends who weren't as familiar with cloud storage technologies, Arq wasn't a great fit. They were expecting something simpler. So in 2018 we created Arq Cloud Backup. In 2020 we merged the 2 products into Arq Premium.
Arq Premium is a subscription service which includes the Arq app plus built-in cloud storage and web access to your backed-up files if you need them on the go.