YCW25· AI· DevtoolsOsmosis
Reinforcement Learning (RL) for AI Agents
Founders
- Kasey ZhangFounder/CEO
- Andy LyuFounder/CTO
Same space
Competitors
Closest in what they build, same category.
CartpoleX25Building reinforcement learning environmentsShared: reinforcement learningActive
hiloopS26Autoresearch as a service: we solve your hardest measurable problemsShared: machine learning, reinforcement learning, infrastructureActive
TrainLoopW25Reasoning Fine-TuningShared: reinforcement learningActive
UnifyW23Models that keep learningShared: reinforcement learning, infrastructureActive
CueBenchS26RL post-training for science reasoning and performance engineeringShared: reinforcement learningActive
Adjacent
Overlapping tags, a different niche.
MonteS25Continual Learning for AgentsShared: reinforcement learning, infrastructureActive
TraverseW26Research lab solving non-verifiable workShared: machine learning, reinforcement learningActive
AviroX25Environments for Long Horizon WorkShared: reinforcement learningActive
LilacS25We sell GPUs.Shared: machine learning, infrastructureActive
TrainyS23Infrastructure for managing GPU clusters for training/serving.Shared: machine learning, infrastructureActive
Also from W25 in AI
Batchmates in Winter 2025.
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BezelW25Digital AI humans that model clothes for e-commerce brands.Active
DextoW25AWS for AI AgentsActive
ExlaW25Building agents that reads logs and fixes issues on your behalf.Active
HUDW25Platform for building RL environments and evalsActive
Outside YC
Similar companies on companies.fru.dev.
About Osmosis
Osmosis is a post-training platform that helps companies fine-tune language models using reinforcement learning. We work with fast-growing AI companies to train task/domain-specific models that beat foundation models on performance, cost, and latency. Our platform handles compute orchestration, reward modeling, and training run observability as a CLI-based product usable by developers and agents.
San Francisco, CA, USA
Osmosis: questions
Which YC batch was Osmosis in?
Osmosis was in Y Combinator's Winter 2025 batch (W25).
Is Osmosis still active?
Y Combinator lists Osmosis as active.
Who founded Osmosis?
Osmosis's founders, as listed on its YC page: Kasey Zhang (Founder/CEO), Andy Lyu (Founder/CTO).
Where is Osmosis based?
Osmosis lists San Francisco, CA, USA as its location on YC's directory.
Not affiliated with Y Combinator. From YC's public directory. Logos via logo.dev; trademarks belong to their owners.