xAI’s Co-founder Igor Babuschkin’s startup River AI has raised $1.1 billion across its Series Seed and Series A rounds, with General Catalyst and AMP PBC leading the funding. NVIDIA and AMD Ventures also invested, alongside Y Combinator and Temasek.
The company said the funding will support its efforts to give developers and enterprises tools to train, fine-tune and own AI models using their own data.
River is building an API that lets companies run reinforcement learning and LoRA fine-tuning on open-weight models without managing the underlying infrastructure.
The company said enterprises can complete reinforcement learning runs in 15 to 20 minutes, while its platform handles weight transfers, sampling-training consistency and elastic compute.
The API charges based on tokens used for training and inference, rather than requiring customers to pay for unused GPU capacity. River said this can reduce costs by two to four times compared with closed-source alternatives.
“The way AI is built today is not how it will be built in the future. AI should be open, freely available, and affordable,” said Babuschkin, co-founder and CEO of River AI.
“It should feel like it is working for the person using it, not the lab that trained it. We started River to allow people and companies to own their intelligence.”
River said its longer-term goal is to build personal AI that learns from individual users and can be controlled by them. The company plans to work across training infrastructure, personalised AI products, continual learning and hardware for running AI closer to users.
The company was founded by a team with experience at xAI and Tesla. Babuschkin previously worked on generative modelling and reinforcement learning at Google DeepMind and led large-scale training efforts at OpenAI before joining xAI.
General Catalyst CEO Hemant Taneja said River’s focus on open-weight models could support US AI development.
“American leadership in AI urgently requires leadership in open-weight models, while maintaining a lead in closed frontier models,” Taneja said. “The core philosophy of putting ownership of intelligence in the hands of the people using it will prove to be on the right side of history for the open-weight ecosystem.”
Marc Bhargava, Managing Director at General Catalyst, said River addresses the gap between AI capabilities and how companies currently use the technology.
“There is a gap between what AI can do and what most companies actually experience,” Bhargava said. “Until now, companies have lacked a cost-efficient way to train, tune, and own custom AI models.”
Babuschkin has worked across several of the major AI labs. Before founding River, he co-founded xAI with Elon Musk, where he worked on infrastructure, model training, multimodal systems and products. He has also held roles at OpenAI and Google DeepMind.
River AI was publicly launched by Babuschkin in June this year with the River API as its first product.
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