While Square officially launched its person-to-person (P2P) payment system, Square Cash, last week, Google is already providing P2P via Google Wallet. With Square Cash, debit card users can quickly send funds by typing the dollar amount they wish to send in the subject line of an email and copying [email protected] as a recipient. The sender receives an enrollment email asking for his or her debit card number. Square has been testing Square Cash since May, when Google also announced that it was launching a P2P system by integrating Google Wallet and Gmail. At the time, the P2P system was only available on Gmail accounts’ computers, not on mobile devices. “It's free to send money if your bank account is linked to Google Wallet or using your Google Wallet Balance, and low fees apply to send money using your linked credit or debit card,” according to a post on Google’s Official Gmail Blog. To send money in Gmail, users hover over the attachment paperclip, click on the “$” icon, enter the amount they wish to send, and press send. We thought Square was ahead of the game in the mobile P2P realm, since it allows the P2P service to be used on iOS and Android devices, via its app. The app creates an email with the dollar amount and the [email protected] email address pre-populated, with a link to Square Cash in the message body, according to Payments Source. However, we discovered that Google quietly made its P2P service available on mobile devices in mid-September, when it launched its new Google Wallet apps for iPhone and Android. Now the only question is: who will come out on top in the mobile P2P war? Google Wallet’s P2P service sports some advantages for shoppers, including a high limit of $10,000 per transaction and ease of use via attaching to a Gmail message. However, Google Wallet’s debit and credit card transactions are not free, as they are with Square Cash, and users have to sign up for a Gmail account if they don’t have one. Disadvantages to Square Cash include a weekly limit of $250. If users link a mobile phone number and Facebook account or verify their full name, Social Security Number and date of birth, the limit is raised to $2,500 per week. Plus – and this is a major drawback – Square Cash does not support credit cards. It accepts only Visa and MasterCard debit cards, not other prepaid cards or ATM cards.