Paypal

PayPal Holdings, Inc. is an American company operating a worldwide online payments system that supports online money transfers and serves as an electronic alternative to traditional paper methods like cheques and money orders.

Cash app

Cash App is a mobile payment service developed by Square, Inc., allowing users to transfer money to one another using a mobile phone app. As of February 18, 2018, the service recorded 7 million active users.

Zelle

Zelle is a U.S.-based digital payments network owned by Early Warning Services, a private financial services company owned by the banks Bank of America, BB&T, Capital One, JPMorgan Chase, PNC Bank, US Bank and Wells Fargo.

Venmo

Venmo is a mobile payment service owned by PayPal. Venmo account holders can transfer funds to others via a mobile phone app; both the sender and receiver have to live in the U.S. Venmo is a type of payment rail. It handled $12 billion in transactions in the first quarter of 2018.