The world is undergoing a digital financial revolution, and even in relatively mature markets such as the U.S. or Western Europe, the evolution of fintech remains at an early stage. On a global scale, digital payment technologies, loans, and other financial services have huge room for growth.

Those companies that play leading roles in this transformation will likely deliver strong returns for shareholders over the long term. I view these three top fintech stocks in particular as being worth adding to your portfolio this year. 

1. Square

Between payment-processing for credit cards and e-commerce, direct user-to-user payments through its consumer-focused Cash App, and its budding loan and financing platform, Square (SQ 2.48%) has a lot of bases covered in the core growth areas of fintech services. In addition, the company has a footprint in the e-commerce services space through its Square Online Store, and has invested in and is supporting the use of cryptocurrencies.

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Square's business is displaying impressive momentum, and it looks well-positioned to continue benefiting from the growth of the digital economy. The company's net revenue surged 140% year over year to $3.03 billion in the third quarter, and its gross profit jumped 59% to $794 million. Gross profit for the company's Cash App surged 212% year over year in Q3 to $385 million.

Admittedly, Square's stock has a growth-dependent valuation. The company's market capitalization sits at roughly $103 billion, which values it at roughly 196 times forward earnings estimates and 7.8 times expected sales. On the other hand, this is a company that has made the right innovation bets, built network advantages, and is primed to benefit from expanding demand and emerging opportunities.

2. Zuora

Zuora (ZUO 0.10%) provides a software platform that offers businesses a highly customizable and easily scalable approach to building subscription-based businesses. Many companies have been pivoting to recurring-revenue-focused models because they tend to make business both more predictable and more profitable. That's a heck of a combination.

Plenty of large companies have already made subscription models a key part of their strategies, but this evolution in the world of business is still at a relatively nascent stage. There's huge room for it to grow. 

Subscription-based models help keep customers on board, allowing companies to spend less on marketing and advertising. For many products and services, they also open the door to generating more revenue over time than would be generated by one-off purchases. These dynamics bode very well for Zuora, and its stock -- which is cheaply valued right now -- could deliver big wins for patient investors. 

Zuora's share price has dipped roughly 12.5% over the last year, with the slump largely stemming from the difficulties the company has had in attracting new customers in this uncertain economic environment. Looking ahead, pressures from the coronavirus pandemic should start to ease. The recent challenges have only delayed the almost inevitable transition of more businesses to subscription-based models.

Zuora looks attractively valued with a market capitalization of roughly $1.6 billion and a forward price-to-sales ratio of 5.3. 

3. PagSeguro Digital

PagSeguro Digital (PAGS -3.40%) is a Brazil-based fintech player that's accelerating the growth of digital commerce in Latin America. It offers mobile and card-based payment processing services for businesses as well as a variety of online banking services for consumers.

Cash is still the primary method of payment for most Brazilians, but the adoption of digital payment technologies is expanding at a rapid clip. The e-commerce market in the country is also still immature compared to the U.S., Europe, China, and many other markets, and its fast growth means PagSeguro will continue to benefit from growing demand for payment-processing services. 

Total payment volume on the company's platform climbed 52.5% year over year in the third quarter, and the company brought roughly 474,000 new merchant partners into its ecosystem in the period. The pandemic created challenges for many businesses in Brazil, but it also resulted in more commerce taking place through digital channels, and the last year's unprecedented conditions have likely accelerated a broader shift. 

PagSeguro is in a great position to shape and capitalize on growth for financial technologies in Brazil and other Latin American markets, and the stock still offers long-term upside even after climbing roughly 46% over the last year. The company now has a market capitalization of roughly $17.3 billion and trades at roughly 43 times this year's expected earnings and 10 times expected sales.

There's huge room for growth for fintech services in Latin America, and PagSeguro can remain one of the leading providers in the space and trounce expectations.