Shopify's reader is an alternative to the popular version sold by Square, which just introduced a prepaid debit card that lets users tap into their Square Cash while shopping at brick-and-mortar stores. PayPal and Intuit also have mobile card readers, while Amazon's short-lived version is no more. Shopify unveiled its new reader in April and began taking select pre-orders last month. Today, the reader is available to all Shopify merchants.

To use Shopify's card reader, you'll have to have nothing older than an iPhone 5 or iPad Gen 3 running iOS 9 or higher or an Android device running version 4.4 at minimum. It's only available in the US and is being offered to new Shopify point-of-sale merchants for free. Everyone else can snag one for $29.