River AI, a startup founded two months ago by xAI co-founder Igor Babuschkin, has raised $1.1 billion in a seed/Series A round led by General Catalyst and AMP PBC, with Nvidia, AMD Ventures, Y Combinator and Temasek also participating. The scale of the investment is striking for such a young company, underlining both the intensity of investor interest in AI infrastructure and River's ambition to rebuild the AI stack from the ground up, focusing on personally trainable agents rather than tools designed to replace human workers.

Babuschkin, who previously worked at DeepMind and OpenAI, envisions "guardian angel"-style agents that know and serve individual users rather than following instructions from prompts alone. River's existing API, priced per million tokens, lets developers apply reinforcement learning and LoRA fine-tuning to open models, positioning the product as an alternative to prompt engineering. The company says enterprises can complete complex reinforcement learning runs in 15 to 20 minutes without a dedicated infrastructure team, at two to four times the cost of closed-source rivals, tapping into growing enterprise appetite for control over open-weight AI models.