Celtra, the developer of a creative management platform for digital advertisers, has raised funding in a round co-led by WPP and Unilever Ventures.

Marketing group WPP and Unilever Ventures, the corporate venturing arm of consumer goods producer Unilever, have co-led a $15m round for US-based digital advertising software provider Celtra.

Celtra has built a cloud-based creative management platform for digital advertisers. WPP and Unilever invested as part of a partnership agreement that will involve Celtra’s technology being used across Unilever’s worldwide marketing organisation.

Keith Weed, Unilever’s chief marketing officer, said: “Creative is an increasingly complex challenge for large advertisers and one that is…