It is easier than ever to send money, pay bills, and make purchases using your smartphone. Peer to Peer (P2P) payment apps let you send funds fast — but are they safe?

First, let’s look at the numbers.

At least 63.5 million adults in the United States use a P2P payment app at least once a month. That’s almost one-third of smartphone users — andt those users have completed more than $120.38 billion in P2P transactions, a number expected to double by 2021.

That means you’ll likely be using these apps — a lot. But before we get into the safety of these apps, there are a number of P2P apps to choose from. Here’s what you need to know about their features.

ZELLE allows users to send money to anyone with a checking account. There are no fees to send, request, or receive money and it has a fast payment processing time — funds are usually available within minutes.

Venmo requires both the person sending the funds and the person receiving them have Venmo. There’s typically a one to three day wait time to transfer funds from Venmo to checking account, but the service is free when it’s linked to a debit card or checking account. To transfer funds to a credit card, there a 3 percent fee.

Paypal also requires both users have PayPal accounts and can also take one to three days to transfer funds to a checking account. It’s free to link to a bank account and costs 2.9 percent of the transaction plus a $0.30 fee to link to a credit or debit card. Unlike Venmo, however, Paypal is available on both desktop and mobile.Apple Pay Cash requires both users have an Apple product with the latest system update installed. It also requires both users access their accounts using Face ID or Touch ID authentication. Users can expect a transaction processing time of 1-3 days, and free service unless you’re linking the transaction to a credit card.

Now that you know about the most popular P2P apps, here’s how to be safe using these apps.

First, you should only ever send cash to people you know: These apps are meant to exchange money between friends, family, and people you know. Be sure you’ve selected the right username, because most P2P apps won’t allow you to cancel a payment once you’ve sent it.

Next, you should continue to monitor your bank accounts on a regular basis to make sure your transactions are going through as intended. Use a money manager to track your spending, your FICO score and other financial records.

Finally, beware of scams. Exchange cash only with people you know to avoid scams from thieves with bogus accounts.