At an event at eBay’s headquarters Thursday, online and mobile payment company PayPal announced partnerships with several point of sale system companies to integrate mobile check ins, electronic receipts, and PayPal integrated cash registers.

“In-store payments are a natural extension of what we’ve done. As mobile has become important, retailers have gotten interested in how they can use mobile as a connective tissue the consumer,” said PayPal’s vice president of retail Don Kingsborough in an interview with VentureBeat.

PayPal has cut deals with VeriFone Systems and Equinox Payments to integrate the company’s payment system into cash registers already present in many retail stores. Both company’s point of sale equipment is found in many large- and medium-sized chain stores, along with smaller businesses.

Verifone has entered “a comprehensive licensing, marketing and implementation agreement” with PayPal for its cash registers. Initially, PayPal’s digital wallet will integrate with Verifone systems, as an alternative payment option. Likewise, the deal with Equinox enables customers to pay with PayPal’s mobile app.

The payment company has also partnered with smaller point of sale system companies Vend, Erply, Shopkeep, and Leapset. Small businesses use their POS software to run their business and accept in-store payments. PayPal’s partnership with Vend and others focuses on mobile payments and check-ins. Customers can check into a store using Vend, Erply, Shopkeep, or Leapset cash registers, pay with the PayPal mobile app, and receive email receipts.

PayPal announced partnerships with several retailers, including JCPenneys, Office Depot, and Jamba Juice, to process mobile payments and offer mobile offers, such as coupons.

The news could threaten mobile payment company Square, which offers payments processed with a smartphone but only with Square-enabled cash registers. Right now, the majority of businesses using Square are small and localized. Now that PayPal has partnered with POS companies whose terminals are used in major retailers, it could hamper Square’s potential growth into larger-scale retailers.

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