River AI raises $1.1B to rebuild AI from scratch with personally trainable agents

River AI, a startup founded by xAI co-founder Igor Babuschkin, has raised $1.1 billion in a seed and Series A round led by General Catalyst and AMP PBC, with participation from Nvidia, AMD Ventures, Y Combinator, and Temasek. The company emerged from stealth just two months ago with a mission to rebuild AI from the ground up—starting with how models are trained—to turn agents into personally trainable assistants rather than worker replacements.

Babuschkin, whose resume includes stints at DeepMind and OpenAI, argues that the current AI stack is fundamentally flawed for personal agents. “To get there, we believe the stack has to be rebuilt end to end: training, models, the product layer, and new hardware that lets personal AI live close to you,” he wrote in his launch blog. He envisions a future where capable agents are “less like the assistants you call on today when you need a task done, more like guardian angels: quietly present, on your side, helping with what actually matters to you. They will know you well, and they will be yours, not someone else’s.”

River’s first product is an API that lets developers fine-tune open models using reinforcement learning (RL) and low-rank adaptation (LoRA), billed per million tokens. The pitch is that this is an antidote to prompt engineering, which only steers a model you don’t own. “River lets you train open models into ones that are truly yours—and serve them like any other endpoint,” the company says.

The funding comes at a time when enterprises increasingly want to control their AI model destiny by mixing open-weight models. River claims that any enterprise can complete a complex reinforcement learning run in 15 to 20 minutes with no infrastructure team, at two to four times the cost savings compared to closed-source alternatives.

The bigger vision is that everyone will have their own agents, trained by themselves, working on their behalf—a concept already visible with locally-running agents like OpenClaw and derivatives, and Nvidia’s partnerships with PC makers for AI-capable hardware. How River’s tech will differ remains to be seen, but it now has a war chest to find out.