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AI Desk · Model Identity

OpenAI: GPT-3.5 Turbo (older v0613)

openai/gpt-3.5-turbo-0613 · OpenAIDeclared and measured agree
Tokenizer lineage (measured)
GPT
Evidence confidence
High
Why high: an exact fingerprint shared with 31 models that declare the same family, without a second signal of a different kind yet.
Declared tokenizer tag
GPT
Entered catalogue
25 January 2024
Last tested
3 September 2026
Measurement
Measured
Evidence
  • ✓ exact tokenizer signature shared with 31 models
Compare with OpenAI: GPT-5.6 Luna

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Identity statement

OpenAI: GPT-3.5 Turbo (older v0613) is OpenAI's model. Its measured tokenizer sits with the GPT group, which is evidence that it builds on the GPT tokenizer. Tokenizer reuse is normal engineering, open vocabularies travel between labs, and this says nothing against OpenAI's authorship of the model itself.

Evidence stack

Signals of different kinds, weighed together
SignalResultReference
Tokenizer signatureExact match with 31 other modelstk_d1411c9d
API surfaceNo other entry shares this exact contractapi_fa93c9dc
Context and output4,095 context · 3,685 max outputdeclared
Reasoning contractNone declareddeclared
Serving providers observedAzuremeasured 3 September 2026

Shares this fingerprint

Exact signature first; template-boundary shifts of the same signature beneath
OpenAI: GPT-4.1openai/gpt-4.1exact · 50/50OpenAI: GPT-4.1 Miniopenai/gpt-4.1-miniexact · 50/50OpenAI: GPT-4.1 Nanoopenai/gpt-4.1-nanoexact · 50/50OpenAI: GPT-4o-miniopenai/gpt-4o-miniexact · 50/50OpenAI: GPT-4o-mini (2024-07-18)openai/gpt-4o-mini-2024-07-18exact · 50/50OpenAI: GPT-5openai/gpt-5exact · 50/50OpenAI: GPT-5 Nanoopenai/gpt-5-nanoexact · 50/50OpenAI: GPT-5.1openai/gpt-5.1exact · 50/50OpenAI: GPT-5.1-Codexopenai/gpt-5.1-codexexact · 50/50OpenAI: GPT-5.1-Codex-Maxopenai/gpt-5.1-codex-maxexact · 50/50OpenAI: GPT-5.1-Codex-Miniopenai/gpt-5.1-codex-miniexact · 50/50OpenAI: GPT-5.2openai/gpt-5.2exact · 50/50OpenAI: GPT-5.2-Codexopenai/gpt-5.2-codexexact · 50/50OpenAI: GPT-5.3-Codexopenai/gpt-5.3-codexexact · 50/50OpenAI: GPT-5.4openai/gpt-5.4exact · 50/50OpenAI: GPT-5.4 Miniopenai/gpt-5.4-miniexact · 50/50OpenAI: GPT-5.4 Nanoopenai/gpt-5.4-nanoexact · 50/50OpenAI: GPT-5.5openai/gpt-5.5exact · 50/50OpenAI: GPT-5.6 Lunaopenai/gpt-5.6-lunaexact · 50/50OpenAI: GPT-5.6 Solopenai/gpt-5.6-solexact · 50/50OpenAI: GPT-5.6 Terraopenai/gpt-5.6-terraexact · 50/50OpenAI: GPT Chat Latestopenai/gpt-chat-latestexact · 50/50OpenAI: gpt-oss-120bopenai/gpt-oss-120bexact · 50/50OpenAI: gpt-oss-20bopenai/gpt-oss-20bexact · 50/50OpenAI: gpt-oss-safeguard-20bopenai/gpt-oss-safeguard-20bexact · 50/50OpenAI: o3 Miniopenai/o3-miniexact · 50/50OpenAI: o3 Mini Highopenai/o3-mini-highexact · 50/50OpenAI: o4 Miniopenai/o4-miniexact · 50/50OpenAI: o4 Mini Highopenai/o4-mini-highexact · 50/50Thinking Machines: Inklingthinkingmachines/inklingexact · 50/50Thinking Machines: Inkling Smallthinkingmachines/inkling-smallexact · 50/50

Closest measured models

Agreement across the mutually clean test strings
OpenAI: GPT-5 Nanoopenai/gpt-5-nano50/50 · 100%OpenAI: gpt-oss-20bopenai/gpt-oss-20b50/50 · 100%OpenAI: gpt-oss-120bopenai/gpt-oss-120b50/50 · 100%OpenAI: gpt-oss-safeguard-20bopenai/gpt-oss-safeguard-20b50/50 · 100%OpenAI: GPT-4.1 Nanoopenai/gpt-4.1-nano50/50 · 100%OpenAI: GPT-4o-miniopenai/gpt-4o-mini50/50 · 100%

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-long17
spaces-203
spaces-603
tabs-203
newlines-204
mixed-ws6

Digits

digits-93
digits-124
digits-3010
digits-sep7
float-long9

CJK

zh-common12
zh-long17
zh-rare20
ja-kana10
ja-kanji13
ko11

Other scripts

ru11
ar11
he10
hi11
th11
el14

Emoji

emoji-basic8
emoji-skin13
emoji-zwj-family11
emoji-zwj-x333
emoji-flags16
emoji-prof20

Rare Unicode

math31
boxdraw27
combining11
cjk-ext-b13
surrogates40
zalgo35
rtl-mix5

Code

py-code25
py-indent15
json20
html16
regex44
camel6
snake6

Repetition and encodings

rare-word-x531
repeat-tok22
base6434
hex11
url17
uuid27

An x marks a row excluded as corrupt (caching or provider interference detected during measurement). Overhead subtracted: 7 prompt tokens.

Declared record

What the catalogue claims about this model

GPT-3.5 Turbo is OpenAI's fastest model. It can understand and generate natural language or code, and is optimized for chat and traditional completion tasks. Training data up to Sep 2021.

Modalities
text->text
Declared tokenizer
GPT
Prompt price
$1.00 / M tokens
Completion price
$2.00 / M tokens

Supported parameters

frequency_penaltylogit_biaslogprobsmax_completion_tokenspresence_penaltyresponse_formatseedstopstructured_outputstemperaturetool_choicetoolstop_logprobstop_p

defaults: {}

Catalogue entry

History

Every observation, kept as taken
  • 25 January 2024Enters the OpenRouter catalogue declared as GPT.
  • 3 September 2026Fingerprinted in the YFarmX catalogue sweep · 50 of 50 strings measured clean.
  • 3 September 2026YFarmX assessment: consistent with the GPT family, high confidence.

Cite this page as the evidence record for OpenAI: GPT-3.5 Turbo (older v0613): the URL is stable, measurements are dated, and revisions append to the history above. Method: tokenizer fingerprinting, v1, 50 strings.