Introducing Corus, our frontier model
Our most capable model is now available to every Ichnus user, free of charge.
Today Corus — the most capable model in the Ichnus family — is available to every Ichnus user, free of charge.
Corus is the model we have been building toward since Curos began. It is the strongest reasoning we have, built for deep research, complex problems, and difficult judgment calls. Its context window is a million tokens, which means it can read and reason over material that would fill a long book.
What Corus is for
Corus is not a faster version of the other models. It is a different kind of tool:
- Deep research. Corus can take a question, read the relevant material across very long documents, and synthesize an answer with citations to what it actually read.
- Complex reasoning. Multi-step problems where an intermediate step can be wrong — math, analysis, planning — are where the bigger model earns its compute.
- High-stakes work. Drafting, decision-support, and analysis where the cost of a confident mistake is high.
For everyday questions, use Mantus. For speed, use Krus. For the hard stuff, this is what Corus is for.
Free, with fair-use limits
Corus is free like everything else at Curos — no paywall, no premium tier, no “pro” version. It is the same model for everyone.
It is also expensive to serve, and that is the tension we are honest about. So Corus comes with fair-use limits: free for the research and problem-solving it is built for, with generous guardrails so one person’s workload cannot crowd out everyone else’s. The limits exist to keep it available, not to sell you an upgrade — there is nothing to upgrade to.
The safety story
Corus went through the full release process: the evaluation suite, the interpretability review, and sign-off by the Safety & Evaluations Committee. The evaluation report is published with the model, and it includes the honest section — what we did not test and why. Frontier models deserve more scrutiny, not less, and we treated the most capable model accordingly.
Why this matters
The argument that power should not be reserved for those who can pay is easy to make and hard to keep. Corus is the test of whether we meant it. A million-token frontier model, free, for anyone. That is the product version of why Curos exists.
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