OuterBox has acquired TopSpot, a Houston-based digital marketing agency specializing in SEO, paid media and website design for the industrial-manufacturing sector. 

The acquisition doubles OuterBox's size, making it one of the largest independent performance-marketing agencies in the U.S.

The deal capitalizes on the offerings of both companies, which include SEO, PPC, UX/CRO, email marketing, analytics and web development. The added muscle expands the digital marketing solutions to clients.

Jeff Allen, CEO of OuterBox, said: "This merger is a significant milestone in our growth strategy, allowing us to greatly extend our industry reach, particularly in the B2B sector."

The 20-year-old OuterBox provides marketing services across multiple platforms, including WordPress, Shopify, BigCommerce and Magento. Clients include Crayola, Lowe's and TronAir.