Urban Airship, a US-based developer of push notification services for smartphones, closed $21m in series D follow-on financing on Friday from investors including Verizon Ventures, the corporate venturing unit of telecommunications network Verizon.
August Capital, Foundry Group, Franklin Park Associates, QuestMark Partners and True Ventures also participated in the financing.
Urban Airship’s platform enables companies to send targeted messages via mobile push messages, in-app messages, rich app pages, Apple Passbook passes and Google Wallet Cards in order to increase customer retention rates.
Urban Airship initially raised $25m in series D funding in 2013 from Verizon and cloud computing company Salesforce.com. It then extended the round in October 2014 with $12.1m from backers including True Ventures, Foundry Group and August Capital, before securing the latest $9m.
Salesforce and Verizon first participated in Urban Airship’s series C round in 2011, which raised $15.1m. In 2010, the company received $6.5m across two rounds from True Ventures, Founder’s Co-Op and Foundry Group.