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OpenAI · Frontier

GPT 5.1

Added Nov 13, 2025

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Use in the app

Optimized GPT-5.1 routing for lower latency and higher availability.

  • Reasoning
  • Tools
  • Vision
  • Structured output
  • PDF input
Input
Text, Images
Output
Text
Reasoning effort
none · low · medium · high
Discovery tier
Frontier

Pricing

USD per 1M tokens
Input
$1.25
Output
$10.00
Cache read
$0.13

Reference prices as published by the model provider. API example

Specifications

Context window
400K
Max output
128K
Average output (7 days)
294 tokens
Longer than 31% of 465 models

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Public evaluations

Benchmarks

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

Intelligence Index

13.3

Better than 33% of 326 scored models

3.8Catalog models by score55.1

Indexes

  • Math Index

    38.0

    Composite of the math evaluations

    Better than 37% of 118 scored models

Document reasoning

  • AA-LCRv1.1

    45.0%

    Reasoning across long documents

    Better than 21% of 309 scored models

Reasoning and knowledge

  • Humanity’s Last Exam

    5.3%

    Expert-level questions across academic fields

    Better than 17% of 323 scored models

  • GPQA Diamond

    64.3%

    Graduate-level science questions

    Better than 21% of 291 scored models

  • MMLU-Pro

    80.1%

    Multi-subject knowledge and reasoning

    Better than 50% of 132 scored models

  • IFBench

    43.2%

    Following precise output instructions

    Better than 36% of 215 scored models

Coding

  • LiveCodeBench

    49.4%

    Recent competitive programming problems

    Better than 41% of 129 scored models

Math

  • AIME 2025

    38.0%

    Competition mathematics, 2025 problems

    Better than 37% of 118 scored models

Legacy evaluations

  • Terminal-Bench Hard

    22.7%

    Earlier terminal task suite

    Better than 42% of 212 scored models

  • τ²-Bench Telecom

    46.5%

    Tool use in a customer-support simulation

    Better than 37% of 214 scored models

  • AA-LCR (unversioned)

    45.0%

    Long-context reasoning, earlier grading

    Better than 21% of 309 scored models

Scores from Artificial Analysis, updated Oct 26, 2026. Artificial Analysis

Live routing data

Performance and reliability

Recent averages across requests routed for this model. Your own speed depends on prompt length, reasoning effort and load.

Prompt cache hits
48.4%
About $0.71 per 1M input tokens with caching
Request success (24h)
100.0%
Reliable

Cache hits are the share of input tokens recently served from a prompt cache across all requests. They are not a forecast of your own hit rate.

Hourly request success · last 72 hoursLowest hour 100.0%
  • Healthy (98% or more)
  • Degraded (90–98%)
  • Down (under 90%)
  • No requests

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",
    "reasoning_effort": "medium",
    "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",
    messages=[{"role": "user", "content": "Explain this stack trace."}],
)
print(reply.choices[0].message.content)

OpenAI

Other OpenAI models, starting with the same family.