Question 1

What is Hermes 4 405B?

Accepted Answer

Hermes 4 405B is a model from Nous Research, released on Aug 26, 2025. 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 \u003cthink\u003e...\u003c/think\u003e 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 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 behavior.

Question 2

How much does Hermes 4 405B cost?

Accepted Answer

On the Respan gateway, input starts at $1.00 per 1M tokens on every provider, and output starts at $3.00 per 1M tokens on every provider, after gateway discounts.

Question 3

Which providers serve Hermes 4 405B on Respan?

Accepted Answer

2 providers serve Hermes 4 405B: Nebius and OpenRouter.

Question 4

What is Hermes 4 405B's context window?

Accepted Answer

Hermes 4 405B accepts up to 131K tokens of context on its largest provider route.

Question 5

How do I use Hermes 4 405B with the Respan gateway?

Accepted Answer

Point any OpenAI-compatible SDK at https://api.respan.ai/api/ with your Respan API key and set the model to "hermes-4-405b". To set it up with a coding agent, copy the agent setup prompt at the top of this page.

Question 6

How fast is Hermes 4 405B?

Accepted Answer

Over the last 30 days of requests through the Respan gateway, the fastest provider was OpenRouter at 24 tokens per second, and the lowest response latency was 0.6 seconds on OpenRouter. Speed varies with request size and provider.

Provider	Context	Input	Output	Capabilities
Nebius`nebius/NousResearch/Hermes-4-405B`	131K	$1.00/M	$3.00/M
OpenRouter`openrouter/nousresearch/hermes-4-405b`	131K	$1.00/M	$3.00/M

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