FIling: Lone Palm Labs, the startup behind friend-focused photo sharing app Retro, raised a $21M Series A from Thrive Capital and others (Sydney Bradley/Business Insider)

Lone Palm Labs, the creator of the friend-focused photo-sharing app Retro, secured a $21 million Series A round led by Thrive Capital along with additional investors. The funding will accelerate Retro’s product development and expand its user base while positioning the startup for further growth in the social-media market.