What is Hermes 4 405B?

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 ... traces or respond directly, offering flexibility between speed and depth. Users can control the reasoning behaviour with the reasoning enabled boolean.

How much does Hermes 4 405B cost?

Hermes 4 405B costs $1.00/M input tokens and $3.00/M output tokens, with separate rates for Cache Read at $0.20/M tokens.

What is the context length of Hermes 4 405B?

Hermes 4 405B has a 131,072 token context window.

Does Hermes 4 405B support tool calling and structured outputs?

No. Hermes 4 405B does not accept tools, so function calling is unavailable. It also supports structured outputs via a JSON schema in response_format.

Which providers serve Hermes 4 405B?

Hermes 4 405B is served by 1 provider on OpenRouter: Nebius Token Factory.

When was Hermes 4 405B released?

Hermes 4 405B was released on August 26, 2025. Its knowledge cutoff is August 31, 2024.

Nous: Hermes 4 405B

nousresearch/hermes-4-405b

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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

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.

Modalities

In / out price

$1 / $3per 1M

Context

131K

Released

Aug 26, 2025

Knowledge cutoff

Aug 2024

Providers

This model is hosted by one provider. OpenRouter forwards every request without routing.

Latency / throughput


	$1.00	$3.00	$0.20	0.35s	38 tok/s	100.00%

Input $1.00Output $3.00
38 tok/s100.00% uptime

Pricing

The average price customers actually pay for this model, next to the prices providers post. Caching and discounts mean the price actually paid is often well below the listed one.

Weighted average

Input

$0.4723/M tokens

Output

$3/M tokens

Hermes 4 405B — Price history

Price history

No effective price data for this selection

		$0.472	$3.00	65.9%	100.0%

Effective in $0.472Effective out $3.00
Token share
100.0%

Uptime

Uptime is the percentage of the past 3 days that at least one provider was responding to requests. Availability is the percentage of time that inference was successfully served. OpenRouter continuously monitors and uses the next-best provider when one returns an error.

Uptime (3d)

100.00%

Availability (3d)

99.95%

Availability over the last 3 days

Last 72 hours

Availability 99.95%

3 Days Ago2 Days AgoYesterdayNow

Availability over the last 24 hours

OpenRouter Availability

99.95%

When an error occurs in an upstream provider, we can recover by routing to another healthy provider, if your request filters allow it. You can access per-provider uptime data programmatically through the Endpoints API. Learn more about our load balancing and provider routing options.

Benchmarks

Scores on standardized evaluations and this model’s own outputs on shared benchmark prompts. Higher percentages are better — and each rank shows where this model lands among the models evaluated on that source.

Benchmark score summary for Nous: Hermes 4 405B (Artificial Analysis)
Source	Benchmark	Score
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Reasoning) GPQA Diamond	72.7%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Reasoning) HLE	10.9%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Reasoning) IFBench	32.7%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Reasoning) τ²-Bench Telecom	22.2%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Reasoning) AA-LCR	22.3%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Reasoning) CritPt	0.3%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Reasoning) LiveCodeBench	68.6%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Reasoning) Terminal-Bench Hard	11.4%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Reasoning) MMLU-Pro	82.9%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Reasoning) AIME 2025	69.7%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Non-reasoning) GPQA Diamond	53.6%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Non-reasoning) HLE	4.2%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Non-reasoning) IFBench	34.8%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Non-reasoning) τ²-Bench Telecom	26.6%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Non-reasoning) AA-LCR	22.0%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Non-reasoning) CritPt	0.0%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Non-reasoning) LiveCodeBench	54.6%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Non-reasoning) Terminal-Bench Hard	9.8%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Non-reasoning) MMLU-Pro	72.9%
Artificial Analysis	Hermes 4 - Llama-3.1 405B (Non-reasoning) AIME 2025	15.3%

Apps

Public apps that send the most traffic to this model. Good signal for what real production workloads look like — and a hint at which use cases this model is best suited for.

SillyTavern

SillyTavern is the LLM frontend for power users, a chat interface that connects to any model and gives deep control through character creation, roleplay, and prompt customization.

179Mtokens

HornyDreams Prompt Improver

new

89.7Mtokens

Voice Agents

new

45.9Mtokens

Janitor AI

Janitor AI is a chatbot platform where users create and chat with custom AI characters for interactive roleplay, storytelling, and immersive fiction.

44.8Mtokens

G0DM0D3-pliny

new

44.1Mtokens

Rest of OpenRouter

74.5M

Top 5 Apps

14.1M

Not currently available through EU in-region routing. In-region routing docs

Frequently asked questions

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Hermes 4 70B is a hybrid reasoning model from Nous Research, built on Meta-Llama-3.1-70B. It introduces the same hybrid mode as the larger 405B release, allowing the model to either respond directly or generate explicit <think>...</think> reasoning traces before answering. Users can control the reasoning behaviour with the reasoning enabled boolean. Learn more in our docs

This 70B variant is trained with the expanded post-training corpus (~60B tokens) emphasizing verified reasoning data, leading to improvements in mathematics, coding, STEM, logic, and structured outputs while maintaining general assistant performance. It supports JSON mode, schema adherence, function calling, and tool use, and is designed for greater steerability with reduced refusal rates.

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