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OpenAI · Efficient

GPT 5.1 Codex Mini

Added Nov 13, 2025

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Use in the app

Lightweight GPT-5.1 Codex path.

  • Reasoning
  • Vision
Input
Text, Images
Output
Text
Discovery tier
Efficient

Pricing

USD per 1M tokens
Input
$0.25
Output
$2.00
Cache read
$0.025

Reference prices as published by the model provider. API example

Specifications

Context window
400K
Max output
128K
Average output (7 days)
136 tokens
Longer than 14% of 468 models

Side by side

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TryQwen3.8 27B TEELing 3.0 FlashMiniMax M2.1All 3

Public evaluations

Benchmarks

Independent evaluation results, with how each score ranks among the models in the Noumen catalog.

Intelligence Index

20.4

Tested at high reasoning effort

Better than 50% of 326 scored models

3.8Catalog models by score55.1

Indexes

  • Math Index

    91.7

    Composite of the math evaluations

    Better than 91% of 118 scored models

Document reasoning

  • AA-LCRv1.1

    66.7%

    Reasoning across long documents

    Better than 43% of 309 scored models

Reasoning and knowledge

  • Humanity’s Last Exam

    18.5%

    Expert-level questions across academic fields

    Better than 45% of 323 scored models

  • GPQA Diamond

    81.3%

    Graduate-level science questions

    Better than 49% of 291 scored models

  • MMLU-Pro

    82.0%

    Multi-subject knowledge and reasoning

    Better than 64% of 132 scored models

  • IFBench

    67.9%

    Following precise output instructions

    Better than 66% of 215 scored models

Coding

  • LiveCodeBench

    83.6%

    Recent competitive programming problems

    Better than 89% of 129 scored models

Math

  • AIME 2025

    91.7%

    Competition mathematics, 2025 problems

    Better than 91% of 118 scored models

Legacy evaluations

  • Terminal-Bench Hard

    33.3%

    Earlier terminal task suite

    Better than 64% of 212 scored models

  • τ²-Bench Telecom

    62.9%

    Tool use in a customer-support simulation

    Better than 50% of 214 scored models

  • AA-LCR (unversioned)

    66.7%

    Long-context reasoning, earlier grading

    Better than 43% of 309 scored models

Scores from Artificial Analysis, updated Oct 26, 2026. GPT 5.1 Codex Mini was tested at high reasoning effort; compare scores measured at the same effort.Artificial Analysis

Developers

Use it through the API

Noumen’s API is OpenAI-compatible: any Chat Completions client works with a base URL and a key.

Read the quickstart
curl https://www.noumen.xyz/api/v1/chat/completions \
  -H "Authorization: Bearer $NOUMEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5.1-codex-mini",
    "messages": [{ "role": "user", "content": "Explain this stack trace." }]
  }'
import os
from openai import OpenAI

client = OpenAI(base_url="https://www.noumen.xyz/api/v1", api_key=os.environ["NOUMEN_API_KEY"])
reply = client.chat.completions.create(
    model="openai/gpt-5.1-codex-mini",
    messages=[{"role": "user", "content": "Explain this stack trace."}],
)
print(reply.choices[0].message.content)

OpenAI

Other OpenAI models, starting with the same family.