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Osmosis

Reinforcement Learning (RL) for AI Agents

Y CombinatorWinter 2025ActiveB2BArtificial IntelligenceMachine LearningReinforcement LearningInfrastructure

What they do

Problem

Companies struggle to post-train and fine-tune language models for specific tasks with better performance, cost, and latency than foundation models.

Solution

A CLI-based post-training platform that orchestrates compute, builds reward models, and runs observable reinforcement learning fine-tuning for language models.

Who it's for

Fast-growing AI companies and their developers building task- or domain-specific language models.

Founders

Kasey Zhang
Founder

Currently: osmosis.ai Previously: gaming founder, VC

Andy Lyu
Founder

Defining how real time systems should be built. Previously worked on data architecture and ecosystem at TikTok recommendations as the 5th and youngest US hire

Open roles 1

Machine Learning Engineer
San Francisco, CA, US · Full-time · $180K - $250K
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