Content-software startup Percolate has scored an investment from WPP Digital, adding servicing of agencies to a business largely consisting of brand clients.

Both companies declined to comment on the size of the investment, but an executive familiar with the matter said it's less than $5 million.

WPP will use Percolate's technology to streamline content creation across multiple agencies and clients, it said in a statement about the partnership. Mark Read, CEO of WPP Digital, expects PR and media agencies to take advantage of the software.

For three-year-old Percolate, the partnership should offer more than just a financial boost. WPP will help the group expand in the U.S. and abroad, the companies added.

"WPP has shown an ability to be a strategic investor and deliver value," co-founder Noah Brier told Ad Age. "That's what was especially appealing."

The startup in late 2012 closed a $9 million series A round of financing led by GGV Capital. It raised a seed round of $1.5 million a year earlier from a group of angel investors including Kenneth Lerer, Sherry Redstone and Path co-founder Dave Morin.

Both Mr. Read and Mr. Brier likened the latest deal to WPP's $5 million investment in Buddy Media. The holding company's stake in the social-marketing company earned it $62 million after it was sold to Salesforce.

Jeff Richards, who led Percolate's A round, was on the board at Buddy Media when it sold a stake to WPP. He now sits on the board of Percolate and likely played a role in the deal. Percolate has also worked closely with WPP while supporting its shops' clients like Unilever and GE.

Preceding the Percolate deal, WPP Digital invested in digital video network Fullscreen.