RigUp, an online staffing platform for the energy industry, raised $300 million in a series D funding round. It brings total funding raised by the firm to $450 million.

Austin, Texas-based RigUp matches contract workers with energy companies in the upstream, renewables, midstream and downstream sectors, according to the company. Gross service volume is estimated to exceed $2 billion.

“RigUp is serving a workforce that, up until now, hasn’t been able to take advantage of the expanded opportunities technology affords,” said Mike Witte, COO and co-founder. “RigUp covers more than 100 energy industry service categories in every oil and gas basin and every major wind and solar region in the continental United States.”

The company was founded in 2014.

“Field work, largely performed by a workforce of highly skilled independent contractors, has typically been staffed through a fragmented network of small brick-and-mortar firms,” said Xuan Yong, CEO and co-founder. “That’s inefficient for the companies that need to quickly staff projects and manage labor costs, and it doesn’t give independent contractors access to all available opportunities.”

The latest funding round was led by Silicon Valley venture capital firm Andreessen Horowitz.

David George, a general partner at Andreessen Horowitz, will join RigUp’s board.

Existing investors also participated in the funding round, including Founders Fund, Bedrock Capital and Quantum Energy Partners. New investors included Baillie Gifford and Brookfield Growth Partners.

Bedrock Capital has invested $80 million in RigUp via six financing rounds.

“Long before ‘gig economy’ became an overused buzzword, the entrepreneurialism and independence of the gig economy was alive and well amongst the women and men of the energy industry,” Geoff Lewis, founder and managing partner of Bedrock Capital, wrote in a post on Medium.