Nous: 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...
Anyone in the Space can @-mention Nous: Hermes 4 405B with the team's shared context - pooled credits, one chat, one memory.
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Verdict
Best for
- Cost-sensitive reasoning and analysis tasks
- Function calling and tool use workflows
- Long-context document processing under budget
- Structured output generation at scale
Strengths
Hermes 4 405B delivers frontier-class reasoning at a significant discount — $1 input versus $3 for GPT-4o or Claude Sonnet 4. The 131k context window handles long documents without chunking, and Nous Research's tuning emphasizes reliable function calling and structured output, making it a strong fit for agentic systems. The Llama 3.3 base gives it solid instruction-following and multi-turn coherence across technical domains.
Trade-offs
Creative writing and nuanced tone control lag behind Claude Sonnet 4 and GPT-4o — expect more utilitarian prose. No vision modality limits use cases compared to multimodal peers. Benchmark data is sparse, so performance on specialized domains (legal, medical) remains unverified in public evals. The model is newer, so community tooling and fine-tuning recipes are thinner than for established Llama releases.
Specifications
- Provider
- nousresearch
- Category
- llm
- Context length
- 131,072 tokens
- Max output
- —
- Modalities
- text
- License
- proprietary
- Released
- 2025-08-26
Pricing
- Input
- $1.00/Mtok
- Output
- $3.00/Mtok
- Model ID
nousresearch/hermes-4-405b
Per-token prices show what the model costs upstream. On Switchy your team draws from one shared org credit pool - one plan, one balance for everyone.
Team cost calculator
5 seats · 80 msgs/day
Switchy meters this against your org's shared credit pool - one plan, one balance for everyone.
Providers
| Provider | Context | Input | Output | P50 latency | Throughput | 30d uptime |
|---|---|---|---|---|---|---|
| nousresearch | 131k | $1.00/Mtok | $3.00/Mtok | — | — | — |
Performance
Benchmarks
Works well with
Top MCPs
Compatibility data comes from first-party telemetry; once we have enough co-usage signal, top MCPs for this model will appear here.
How Switchy teams use it
Starter prompts
Multi-Document Analysis
I'm providing three research papers below. Identify the three most significant points of disagreement across them, then propose a synthesis that reconciles these differences. Cite specific sections by paper title.Open in a Space →
Function-Calling Agent
You have access to functions: search_database(query), send_email(to, subject, body), create_calendar_event(title, time). A user says: 'Find all invoices from Q4 and email a summary to finance@company.com.' Plan and execute the necessary function calls.Open in a Space →
Structured Data Extraction
Extract all company names, funding amounts, and investor names from the following press release. Return a JSON array where each object has fields: company, amount, investors (array), date.Open in a Space →
Long-Context Summarization
Summarize the attached 50-page technical specification into a two-page executive brief. Preserve all critical requirements, timelines, and risk callouts. Use bullet points for clarity.Open in a Space →
Cost-Optimized Reasoning
A train leaves City A at 60 mph. Another leaves City B (300 miles away) at 90 mph, heading toward City A. A bird flies back and forth between the trains at 120 mph until they meet. How far does the bird travel? Show your reasoning step-by-step.Open in a Space →
Example outputs
Illustrative - representative of the model's voice and quality, not literal recordings.
Review this Python function for potential race conditions and suggest thread-safe alternatives. Focus on the shared state access patterns.
This function has two critical race conditions. First, the counter increment on line 14 isn't atomic — between read and write, another thread could modify the value. Second, the cache dictionary access on lines 22-24 lacks synchronization, risking corrupted reads during concurrent writes. Replace the counter with `threading.Lock()` or `atomic.AtomicInteger` if available. For the cache, wrap access in a `threading.RLock()` or switch to `collections.OrderedDict` with explicit locking. The performance cost is ~2-3µs per operation, acceptable given your 50ms average request time.
Demonstrates strong concurrency analysis with specific line references and quantified trade-offs. The 131K token context window allows reviewing entire codebases in one prompt. Output stays technical without over-explaining basics, matching the model's positioning for experienced developers.
Explain the Byzantine Generals Problem to a product manager who needs to understand why our distributed system can't guarantee instant consistency across all nodes.
Imagine three generals surrounding a city, communicating by messenger. They must all attack together or all retreat — a split decision means defeat. But messengers can be captured, so how do they agree when they can't trust every message arrives? That's your distributed system. When a user updates their profile, that change must reach five data centers. Network delays mean Center A might see the update before Center B does. Guaranteeing all centers show identical data instantly requires waiting for every confirmation — killing your 50ms response time target. We chose 'eventual consistency': updates propagate in ~200ms, but reads might briefly show stale data.
Shows the model's ability to translate complex technical concepts into business context without losing accuracy. The analogy-first structure and concrete numbers (50ms, 200ms) make abstract distributed systems concepts actionable. At $3/Mtok output, this explanation-heavy use case is cost-effective compared to models with higher reasoning taxes.
Generate a SQL migration script that adds audit logging to our users table while maintaining zero downtime. Include rollback steps and explain the staging approach.
```sql -- Migration 001: Add audit columns ALTER TABLE users ADD COLUMN updated_by VARCHAR(255); ALTER TABLE users ADD COLUMN updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP; CREATE INDEX idx_users_updated_at ON users(updated_at); -- Migration 002: Backfill existing rows UPDATE users SET updated_by = 'system', updated_at = created_at WHERE updated_at IS NULL; -- Migration 003: Add NOT NULL constraint ALTER TABLE users ALTER COLUMN updated_by SET NOT NULL; ``` Staging: Deploy migrations 001-002 first. Your application can write to new columns but doesn't require them yet. Monitor for 24 hours. Then deploy code that populates these fields. Finally, run migration 003 to enforce constraints. Rollback: Drop the index, then drop both columns. No data loss since audit fields are additive.
Illustrates practical DevOps reasoning with a phased deployment strategy that respects production constraints. The model structures the response for copy-paste execution while explaining the 'why' behind each stage. The 131K context window means you could include your entire schema definition in the prompt for more precise migrations.
Use-case deep-dives
When 128k context beats chaining for contract review teams
A 4-person legal ops team processing vendor agreements needs to cross-reference clauses across 8-12 contracts per deal. Hermes 4 405B's 131k token window fits roughly 90k words—enough to load all contracts in a single prompt and ask comparative questions without chaining or RAG overhead. At $1/$3 per Mtok, a typical 80k-token input with 2k output costs $0.086 per analysis. The trade-off: if your team runs more than 300 analyses per month, Claude 3.5 Sonnet's $3/$15 pricing starts to hurt less than the lack of public benchmarks here. Below that threshold, the context window and price make this the default for synthesis work where you need the model to see everything at once.
Why early-stage dev teams pick this for API reference builds
A 3-engineer startup shipping a developer API needs to generate reference docs from 40k lines of annotated TypeScript. Hermes 4 405B's 131k window handles the entire codebase in one pass, and at $1 input per Mtok, scanning 60k tokens of code costs $0.06—cheap enough to regenerate docs on every release. The 405B parameter count suggests strong code understanding, though without public benchmarks you're betting on Nous's reputation rather than hard numbers. If your docs need to stay under $5/month in generation costs and you're not shipping daily, this works. Once you hit 20+ regenerations per week, GPT-4o's faster inference and proven code benchmarks become worth the switch.
When high-volume support teams should look elsewhere first
A 12-person support team handling 400 tickets daily needs to summarize threads into CRM notes. Each summary averages 3k input tokens and 150 output tokens—at $1/$3 per Mtok, that's $0.0012 + $0.00045 = $0.00165 per ticket, or $660/month at volume. The 131k context window is overkill here; most tickets fit in 8k. Without public benchmarks on instruction-following or summarization quality, you're flying blind compared to GPT-4o mini ($0.15/$0.60) or Haiku ($0.80/$4.00), both proven on support workloads. Use Hermes 4 405B if you're already locked into the Nous ecosystem for other tasks and need one model for everything. Otherwise, start with a cheaper, benchmarked alternative and switch only if quality gaps appear.
Frequently asked
Is Hermes 4 405B good for complex reasoning tasks?
Yes. The 405B parameter count puts it in the same weight class as GPT-4 and Claude Opus, which typically excel at multi-step reasoning, code generation, and nuanced instruction-following. Nous models historically prioritise uncensored outputs and instruction adherence, making this suitable for technical work requiring both depth and flexibility. The 131k context window handles long documents or codebases without truncation.
Is Hermes 4 405B cheaper than GPT-4o or Claude Opus?
Yes, significantly. At $1/$3 per Mtok, Hermes 4 costs roughly 60-75% less than GPT-4o ($5/$15) and Claude Opus 4 ($15/$75) for comparable parameter scale. If you're processing high volumes or need a 400B-class model without enterprise pricing, this is one of the most cost-effective options available. Output tokens are where you'll save most.
Can Hermes 4 405B handle 128k token inputs reliably?
The advertised 131k window is there, but real-world performance at maximum context depends on your prompt structure and the model's training. Most 400B-class models degrade slightly past 100k tokens—expect accurate retrieval and reasoning up to ~100k, with some quality drop beyond that. Test your specific use case if you're regularly hitting the upper limit.
How does Hermes 4 405B compare to Llama 3.3 70B?
Hermes 4 has 6x the parameters, so it should outperform Llama 3.3 70B on reasoning depth, code complexity, and instruction nuance. You'll pay 2-3x more per token, but the gap matters for tasks where 70B models plateau—legal analysis, advanced math, or multi-file refactoring. For simpler tasks, Llama 3.3 70B is the better value.
Should I use Hermes 4 405B for production chatbots?
Only if you need the reasoning horsepower and can tolerate the cost. At $3/Mtok output, a chatbot generating 500-word responses costs ~$0.004 per message—manageable for B2B or premium products, expensive for consumer scale. Latency will be slower than smaller models. For general chat, start with a 70B model and escalate to Hermes 4 only when users hit complexity limits.