River AI raises $1.1B to let developers own their models

River AI, a startup founded two months ago by former xAI co-founder Igor Babuschkin, raised $1.1 billion in a seed and Series A round led by General Catalyst and AMP PBC, TechCrunch reported.

Nvidia and AMD Ventures joined as strategic investors, with Y Combinator and Temasek also participating, according to TechStartups. Babuschkin previously worked at DeepMind, OpenAI and xAI.

River offers an API that lets developers fine-tune open-weight models from 35 billion to 1 trillion parameters using reinforcement learning and low-rank adaptation, charging for training and inference rather than idle GPU time, TechStartups reported. "AI should be open, freely available, and affordable. It should feel like it is working for the person using it, not the lab that trained it," Babuschkin said.

River says enterprises can complete a reinforcement learning training run in 15 to 20 minutes without maintaining their own infrastructure team, at two to four times the cost savings of closed source alternatives, according to TechCrunch.

For developers who don't want to depend on a closed model's roadmap, a nine-figure-funded company now sells infrastructure built specifically for retraining and owning open weights instead of prompting someone else's model. Worth a look for any team already building on open weights.