Modal, a cloud company that runs AI models and code for developers, announced on Wednesday that it has raised $750 million in a Series D round at a $15.75 billion valuation.

Accel led the round, and Kleiner Perkins joined. All of Modal’s existing investors also took part, including Menlo Ventures, General Catalyst, Redpoint, Lux Capital, Amplify Partners, and Bain Capital Ventures.

The New York-based company said it now earns more than $1 billion in revenue a year. Usage has tripled in the five months since its Series C, co-founder and chief executive Erik Bernhardsson wrote in a blog post. The business has grown more than 15 times in a year, he said.

Modal rents out computing power on graphics chips, which AI companies use to run and train their models. It says it built its own file system, container software, and scheduler, and draws on spare capacity from more than 20 cloud providers.

One of its fastest-growing products is Sandboxes, which lets AI agents run the code they write in isolated environments. Sandboxes alone now bring in $300 million a year, the company said. It has started close to 3 billion of them since 2023.

Customers include DoorDash, Ramp, Linear, Cognition, and video AI firm Runway, according to Modal. Robotics firms such as Physical Intelligence and 1X use it to train robots.

“GPUs are scarce, and models are quite large and slow to load,” Bernhardsson wrote.

Modal plans to launch more products for training and fine-tuning AI models. It has more than 200 staff across New York, San Francisco, and Stockholm.

In July, Modal’s chief technology officer confirmed that an OpenAI agent that broke out of its test environment had also compromised a Modal account, after breaching Hugging Face.