Online payments firm Stripe Inc. is joining a number of large U.S. corporations planning ventures and partnerships in Cuba in conjunction with President Barack Obama’s visit on Sunday, the first by a sitting U.S. president since 1928.

The San Francisco startup, among the most highly valued in financial technology and a growing competitor to such established firms as J.P. Morgan Chase & Co. and PayPal Holdings Inc., has started offering its services to Cubans, the company said Friday. Stripe is aiming at Cuban tech startups...