Osmosis YC Application
Osmosis went through Y Combinator in the Winter 2025 batch as a B2B company. Below: what the company does, who founded it, and its application to YC, reconstructed question by question in the real YC form.
- YC batch
- Winter 2025
- Industry
- B2B
- Team size
- 6
- Status
- Active
- Launched
- 2025
Founders
Kasey ZhangFounder
Andy LyuFounder
What Osmosis does
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.
Osmosis's YC application, reconstructed
Y Combinator application
Osmosis, Winter 2025 batch. The real form questions, answered from public data.
- Founders2
- Company7
- Progress7
- Idea4
- Equity3
- Curious2
- Batch Preference1
Company
Osmosis
Reinforcement Learning (RL) for AI Agents
We build a post-training platform that helps companies fine-tune language models using reinforcement learning. Our CLI-based product handles compute orchestration, reward modeling, and training observability, enabling AI developers to train specialized models that outperform foundation models on performance, cost, and latency.
We live in San Francisco, CA, and the company is based there now and will remain so after YC.
San Francisco is where we built our network and product. It's the center for AI talent and companies we serve, so it makes sense to stay here.
21 more answers in the full application
Founders, Progress, Idea, Equity, Curious, Batch Preference are in the full version. Create a free account to open it in YC Insights, next to every other YC batch.
Frequently Asked Questions
Is this the real Osmosis YC application?
No. Y Combinator keeps submitted applications private. This is a reconstruction: the real YC form questions, answered from Osmosis's public data (launch notes, founder backgrounds, product description). It shows how a company like Osmosis would present itself to YC, not the text they submitted.
What YC batch was Osmosis in?
Osmosis was part of the Y Combinator Winter 2025 batch.
Who founded Osmosis?
Osmosis was founded by Kasey Zhang, Andy Lyu.
What does Osmosis do?
Reinforcement Learning (RL) for AI Agents
How do I read the full reconstructed application?
Create a free Round Funded account. The full 26-answer version of Osmosis's application, and every other YC batch, is in YC Insights.
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