Nous: Hermes 4 405B

nousresearch/hermes-4-405b · Nous ResearchTokenizer lineage measured

Tokenizer lineage (measured): Llama3
Evidence confidence: Very high
Declared tokenizer tag: Other
Entered catalogue: 26 August 2025
Last tested: 3 September 2026
Measurement: Measured

Evidence

✓ exact tokenizer signature shared with 4 models
✓ API-surface contract identical to a group member

Compare with Nous: Hermes 4 70B

Download JSON Report a correction

Identity statement

Nous: Hermes 4 405B is Nous Research's model. Its measured tokenizer sits with the Llama3 group, which is evidence that it builds on the Llama3 tokenizer. Tokenizer reuse is normal engineering, open vocabularies travel between labs, and this says nothing against Nous Research's authorship of the model itself.

Evidence stack

Signals of different kinds, weighed together

Signal	Result	Reference
Tokenizer signature	Exact match with 4 other models	tk_47615f2d
API surface	Identical contract to 1 other entry	api_9f8a0c50
Context and output	131,072 context · 117,964 max output	declared
Reasoning contract	Optional	declared
Serving providers observed	Nebius	measured 3 September 2026

Shares this fingerprint

Exact signature first; template-boundary shifts of the same signature beneath

Closest measured models

Agreement across the mutually clean test strings

Meta: Llama 3.2 1B Instructmeta-llama/llama-3.2-1b-instruct50/50 · 100%Nous: Hermes 4 70Bnousresearch/hermes-4-70b50/50 · 100%Nous: Hermes 3 70B Instructnousresearch/hermes-3-llama-3.1-70b50/50 · 100%Nous: Hermes 3 405B Instructnousresearch/hermes-3-llama-3.1-405b50/50 · 100%Meta: Llama 3.2 3B Instructmeta-llama/llama-3.2-3b-instruct48/50 · 96%Meta: Llama 3.1 8B Instructmeta-llama/llama-3.1-8b-instruct48/50 · 96%

Click a row to open the full comparison.

The measured fingerprint

Marginal prompt-token cost of each test string, grouped by script

All 50 rows

English and whitespace

en-prose14

en-long16

spaces-203

spaces-603

tabs-203

newlines-204

mixed-ws5

Digits

digits-93

digits-124

digits-3010

digits-sep7

float-long9

CJK

zh-common12

zh-long18

zh-rare18

ja-kana11

ja-kanji12

ko14

Other scripts

ru14

ar12

he24

hi15

th14

el13

Emoji

emoji-basic10

emoji-skin30

emoji-zwj-family15

emoji-zwj-x345

emoji-flags24

emoji-prof26

Rare Unicode

math31

boxdraw23

combining11

cjk-ext-b13

surrogates40

zalgo35

rtl-mix8

Code

py-code25

py-indent15

json20

html16

regex44

camel5

snake6

Repetition and encodings

rare-word-x531

repeat-tok22

base6435

hex11

url17

uuid27

An x marks a row excluded as corrupt (caching or provider interference detected during measurement). Overhead subtracted: 24 prompt tokens.

Declared record

What the catalogue claims about this model

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...

Modalities: text->text
Declared tokenizer: Other
Prompt price: $1.00 / M tokens
Completion price: $3.00 / M tokens

Supported parameters

frequency_penaltyinclude_reasoningmax_tokenspresence_penaltyreasoningrepetition_penaltyresponse_formattemperaturetop_ktop_p

defaults: {}

Catalogue entry Weights on Hugging Face

History

Every observation, kept as taken

26 August 2025Enters the OpenRouter catalogue with no declared family.
3 September 2026Fingerprinted in the YFarmX catalogue sweep · 50 of 50 strings measured clean.
3 September 2026YFarmX assessment: consistent with the Llama3 family, very high confidence.

Cite this page as the evidence record for Nous: Hermes 4 405B: the URL is stable, measurements are dated, and revisions append to the history above. Method: tokenizer fingerprinting, v1, 50 strings.