GBT said the acquisition, which it expects to close in the fourth quarter of this year, reflects its intensified focus on digital business traveller tools over the past two years.
KDS' main product, Neo, is a web, tablet and smartphone service in which travellers can put together complete, bookable door-to-door business travel itineraries and predict their related expenses.
The software as a service firm has operations in France, Germany, the UK and the US. GBT did not disclose the value of the deal.
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"As a part of GBT, KDS will have access to a strong brand, significant resources, broad geographic reach and a large global customer base," said GBT's chief commercial and technology officer Philippe Chereque. "This will open up new possibilities for both businesses, and allow us to provide KDS' innovation to more companies than ever before."
Dean Forbes, chief executive of KDS, said: "KDS is a leading integrated travel technology provider with a deserved reputation for innovation and an entrepreneurial DNA. We have the best team challenging the status quo and creating game-changing technology.
"We look forward to leveraging the support and assets that GBT will provide us to better serve GBT customers, whilst also continuing to serve our existing customers and partners with great products and services."