Nous: Hermes 4 405B
By Nousresearch
Released: 2025-08-26
Nousresearch Hermes 4 405B, developed by Nous Research, features 405B parameters and 131k-token context window. Hermes 4 is a large-scale reasoning model built on Meta-Llama-3.1-405B and released by Nous Research. It introduces a hybrid reasoning mode, where the model can choose to deliberate internally with <think>...</think> traces or respond directly, offering flexibility between speed and depth. Users can control the reasoning behaviour with the `reasoning` `enabled` boolean. [Learn more in our docs](https://openrouter.ai/docs/use-cases/reasoning-tokens#enable-reasoning-with-default-config) The model is instruction-tuned with an expanded post-training corpus (~60B tokens) emphasizing reasoning traces, improving performance in math, code, STEM, and logical reasoning, while retaining broad assistant utility. It also supports structured outputs, including JSON mode, schema adherence, function calling, and tool use. Hermes 4 is trained for steerability, lower refusal rates, and alignment toward neutral, user-directed behaviour. Premium pricing at $1.0/1M tokens reflects its advanced capabilities.
Visit Nous: Hermes 4 405BAI-Powered
Leverages advanced AI technology to deliver cutting-edge capabilities and results.
Fast & Efficient
Optimized performance ensures quick results without compromising on quality.
Purpose-Built
Specifically designed for llms tasks and workflows.
Nousresearch Model Timeline
131k tokens context
131k tokens context
33k tokens context
66k tokens context
131k tokens context
131k tokens context
8k tokens context
Specifications
AI Evaluation
Combines language understanding with search capabilities. Excels at finding and synthesizing information from various sources.
Pros
- 131k token context window
- Large-scale 405B architecture
- Advanced logical reasoning
- Native function calling
Cons
- Moderate API costs
- Requires substantial compute
- Speed/quality trade-off
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