The deal, which was backed by private equity firm and North Plains shareholder Accel-KKR, will combine North Plains' modular DAM platform, TeleScope, with Xinet's WebNative Suite.
In addition, the acquisition significantly boosts North Plains' footprint outside North America - particularly in the EMEA and Asia Pacific (APAC) regions, where Xinet's WebNative Suite has a strong presence.
North Plains chief executive James Christopher said that around two thirds of Xinet's revenue was realised through channel partners in EMEA and APAC, whereas North Plains' focus has been on direct sales into the North America market.
He added: "Xinet's strong channel relationships and market share in EMEA and APAC were two of the key factors that appealed to North Plains in making this acquisition."
North Plains will continue to sell and support both TeleScope and WebNative and it anticipates "a more seamless product integration" going forward.
Christopher added that North Plains would continue to work with Xinet's channel partners while creating a specific reseller program and certification scheme for its own TeleScope DAM platform.
"In the interim, North Plains will roll out an agency program that will compensate Xinet's resellers who bring opportunities to North Plains' sales department," he added.
Xinet chief executive Scott Seebass, who will join the board of North Plains as vice president of engineering and share some of the responsibilities of the chief technology officer role, said: "We have grown Xinet based on the strength of our software and our ability to address the needs of creative talent within organizations.
"Like Xinet, North Plains’ deep focus on DAM and their equal passion for delivering innovative products and services allows us to jointly provide our customers unparalleled products, services and solutions for rich media."
The acquisition comes just over a year after Accel-KKR bought an undisclosed stake in North Plains, with the company announcing its intention to use the extra capital to fund its expansion plans.
Accel-KKR managing director Rob Palumbo said: "Accel-KKR is excited to support North Plains' in its acquisition of Xinet. We believe that by combining two innovative and industry leading rich media management providers, who serve clients that span from small creative groups to the global marketing teams in some of the worlds largest companies, we strategically position North Plains for continued and sustained growth."