The financial details of the investment were not disclosed.
As part of this investment, ACI and Mindgate will deliver a joint real-time payments solution that will combine ACI's Universal Payments software solutions with Mindgate's digital overlay services.
The solution would be offered to banks, financial intermediaries and merchants in India and other international markets via an on-premise, public cloud or hosted model, ACI Worldwide said.
"The global real-time and digital payments transaction opportunity is vast. With Mindgate and ACI alliance, we are well-positioned to capitalise on this growth opportunity by providing to banks, corporates, merchants and payment intermediaries the world's leading real-time payments offering," Phil Heasley, President and CEO, ACI Worldwide, said in a statement.
This investment is also expected to provide Mindgate, a leading firm in processing UPI (unified payments interface) transactions, with the ability to expand its footprint globally.
UPI is a mobile-based, real-time payments platform in India developed and managed by the National Payments Corporation of India (NPCI).
It enables bank account holders in India (of banks participating in the UPI scheme) send and receive money from their smartphones with a single, simple identifier.
"The combination of ACI and Mindgate will support the continued global adoption of real-time and digital payments, while helping to drive UPI as it becomes the dominant Indian retail payments method," AP Hota, former CEO of National Payments Corporation of India (NPCI), said.
According to Mindgate, its software processes 30 million digital transactions a day globally, and 70 per cent of UPI transactions are routed through Mindgate-customer banks.
( With inputs from IANS )