Osmosis is a San Francisco reinforcement learning platform (YC W25) that helps companies fine-tune open-source models to beat foundation models on cost, latency, and reliability. Founded by Kasey Zhang and Andy Lyu, it lets teams train task-specific AI agents with multi-turn tool use over the Model Context Protocol, then export or self-host the weights they own.

Predibase was a San Francisco-based AI infrastructure company (founded 2020, acquired by Rubrik in June 2025) that pioneered efficient LLM fine-tuning and serving at scale. Built by the creators of Uber AI's Ludwig and Horovod frameworks, Predibase made it easy for enterprises to fine-tune and deploy open-source LLMs using LoRA adapters — often outperforming GPT-4 on domain-specific tasks for under $8 of compute. Its open-source LoRAX inference server enabled serving thousands of fine-tuned models from a single GPU, dramatically cutting costs. After raising $28M from Greylock and Felicis, Predibase was acquired by cybersecurity firm Rubrik for over $100M to accelerate agentic AI adoption.