Behavioral analytics company Qubit plans to expand its retail client base and double its engineering staff with a $40 million round of funding.

The Series C funding round, led by Goldman Sachs Merchant Banking division and announced Monday, brings the company’s  fundraising to $76 million since November 2010. Sapphire Ventures joined as a new investor, along with previous lenders Accel and Salesforce Ventures. David Reis, managing director and head of technology at Goldman Sachs Merchant Banking division in Europe, will join Accel’s Bruce Golden and earlier investor Balderton Capital general partner Bernard Liautaud on the board of directors.

“We’re in a growth stage, so we want to grow our numbers of customers and staff and expand in all of our markets,” says Qubit CEO Graham Cooke, who spent five years at Google Inc. in charge of conversion rate optimization for e-commerce sites. He left in 2010 to start Qubit with three other ex-Google employees. The company is based in London.

Cooke says Qubit plans to expand the number of customers it has in its existing markets in the United States, the U.K. and in Europe.

Qubit provides a web-based dashboard for retailers to measure customers’ on-site behavior and to segment them into groups for A/B testing, and an application programming interface to access data from retailers’ systems. As a result, retailers get insights into how their customers act as they shop online, and they can track consumers who enter the retailer’s website from an app, email, mobile devices, advertising, a call center, search engines and other social media, Cooke says.

Farfetch, an online marketplace for luxury fashion goods, for example, used Qubit to test a way to help customers who seemed hesitant or confused. The Qubit technology identified shoppers who spent a long time hovering over a product listing, and Farfetch would display a message to those shoppers suggesting “shop our edits” or try browsing through the men’s or women’s collections, says Kelly Kowal, digital marketing director at Farfetch.

Qubit’s pricing depends on clients’ volume of web traffic, Cooke says. He says most of the vendor’s customers generate at least $10 million in annual online sales. Qubit has 270 retail customers, including U.S. clients Staples (No. 4 in the Internet Retailer 2015 Top 500 Guide), Saks Fifth Avenue (No. 97), Nine West Holdings Inc. (No. 215) and LivingSocial Inc. (No. 206). In the United Kingdom and Europe, Qubit’s customers include John Lewis Plc (No. 11 in the Internet Retailer 2015 Europe 500), ShopDirect.com (No. 10), Topshop (No. 68), Net-a-Porter (No. 31) and Mothercare UK Ltd.  (No. 120).

Qubit added five web tools to its platform in 2015 and has grown its average account size by more than 40%, according to the company.