Edinburgh-based Kestros already has contracts with several NHS trusts, including Ayrshire and Arran, for products such as the MiCheckin app, which allows patients to keep track of appointments. The firm's Repeat Visit Alert system sends a text message to clinical staff when a patient with a known condition is taken into hospital.
Craneware, which is also based in Edinburgh, will pay up to £1.25 million to buy the company and take on its five members of staff. Kestros, founded in 2009, is currently owned by its founder Manjit Mooker and head of development Calum McRae.
"We believe Kestros, with its highly innovative and sophisticated mobile application, which is currently in use in the NHS, has significant potential for expansion," said Craneware chief executive Keith Neilson in a statement yesterday.
"The governments in both the US and the UK are pushing for greater IT links between patients and healthcare providers, meaning both markets are highly receptive to innovative technologies such as Kestros'."
London-listed Craneware will pay £150,000 in cash for the firm and hand out the remainder in new company shares, depending on the firm hitting revenue targets.
Craneware said Kestros' software will fit well with its existing products, which include medical billing programmes and pharmacy supply trackers. The group said it has contracts with almost a quarter of all hospitals registered in the United States.
The company employs more than 200 people at offices in Edinburgh and four US states.
The company also announced yesterday that it has appointed American healthcare veteran Russ Rudish as its new non-executive chairman. Mr Rudish most recently worked for consulting giant Deloitte as its global healthcare leader.