As world grapples with tech monopolies, can India's hard cap be a solution?

From Washington to Beijing, governments are trying to strike the right balance between enabling technology innovation and preventing giants like Google and Facebook Inc. from suffocating rivals. Now India is experimenting with a framework for financial technology that’s certain to provide lessons worldwide -- succeed or fail.

The country’s unique approach is to decree limits on fintech competitors from the start: No single player can grab more than 30% of total payments transactions. Every company also has to use India’s open payments platform, guaranteeing interoperability so money can be transferred between any of more than 100 traditional banks and digital