Meet Ox Alpha.
The reasoning model that appeared out of nowhere — built for code, long-horizon agents, and a million tokens of context. This is an independent field guide: what it is, what we tested, and how to use it.
Reasoning, always on
Ox Alpha thinks before it answers. Reasoning is mandatory and streams as a visible chain of thought, with three effort levels — low, high, and max. You see the working, not just the conclusion.
A million tokens of context
A 1,048,576-token window means you can drop an entire codebase, a book, or a year of logs into a single prompt — no chunking, no retrieval plumbing, no lost-in-the-middle gymnastics.
Built for real work
Long-horizon coding, tool / function calling, and multimodal input. It's designed for sustained agentic workflows, not one-shot party tricks.
What people build with it
All use cases →Ox Alpha at a glance
The specs that matter, verified against the live API.
What we actually tested
Leaderboard claims are easy to make and hard to trust for a model with no named creator. So instead, here are first-hand checks against the live API.
FAQ
Who made Ox Alpha?
Nobody knows publicly. It appeared on OpenRouter under the 'Stealth' provider with its origin masked. That anonymity is part of why it's called a stealth model.
Is it really free?
During the stealth period, yes — every call in our testing returned a cost of $0. That can change without notice once the preview ends, so don't build a business on the price staying zero.
What is it good at?
Coding, long-horizon agent work, and anything that benefits from a huge context window plus real reasoning. It also accepts images and video as input.
Should I send sensitive data?
No. It's a preview model routed through a shared stealth pool that may log traffic. Keep secrets, credentials, and personal data out of your prompts.
How do I use it?
Through the OpenRouter chat-completions API with model 'stealth/ox-alpha'. See the API guide on this site for a copy-paste quickstart.
Try it in your browser
A live chat with streaming answers and visible reasoning — free while Ox Alpha is in stealth.