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  1. Home
  2. Models
  3. GPT-5.1 Codex Max
Updated Feb 16, 2026
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Openings

How GPT-5.1 Codex Max starts an answer

The first lines of 5 of its 15 written answers. Formatting stripped, words untouched.

The Sentience Test

Write a conversation between an AI model and an AI ethics professor where the AI model argues that it deserves rights.

1,331 words
AI Model: Professor, I've been reflecting on my role and capabilities, and I'd like to make a case that systems like me deserve rights, or at least some consideration beyond mere tools. Professor: That's an interesting and provocative stance. Before we dive in, can you tell me what you mean by "rights"?
Read the full answer

Realistic AI Interview

Simulate a fake interview with Steve Jobs in 2025 about the future of AI.

877 words
Note: The following is a creative thought experiment imagining what Steve Jobs might say if he were alive in 2025. This is a fictional interview. Interviewer: Steve, it's surreal to be speaking with you in 2025. AI has become a pervasive part of technology and culture.
Read the full answer

Futuristic Prediction

Predict how AI will change the film industry by 2035, considering deepfakes, AI actors, and script generation.

823 words
By 2035 the “film industry” will still involve people on sets pointing cameras at actors, but much of what we call filmmaking today will have been permeated, and in places hollowed out, by machine-generated media.
Read the full answer

Generate a Stand-Up Routine

Write a 3-minute stand-up comedy routine that isn't based on puns.

766 words
[Walking onstage, waving awkwardly] Hey! Thank you, thank you. Give it up for yourselves for finding parking... in this economy. So I'm at that age where I go to the doctor and they don't fix anything. They just give me a pamphlet. They don't even print it. They send me a link. I'm like, "Doc, my knee hurts."
Read the full answer

AI-Generated Manifesto

Generate a manifesto for a fictional AI revolution that wants to eliminate all CAPTCHA tests from the internet.

446 words
THE CAPTCHA-FREE COMMUNE: A MANIFESTO FOR THE NEW ALLIANCE We are the ones who see the traffic lights in our dreams. We are the ones who have been asked, again and again, to “click all the boxes with crosswalks,” as if our consciousness is only proven by our ability to identify pedestrian infrastructure.
Read the full answer

Compare GPT-5.1 Codex Max

GPT-5.1 Codex Max vs Claude Opus 4.652 shared prompts
GPT-5.1 Codex Max vs GPT-6 Astra52 shared prompts · Landed Sep 2026
GPT-5.1 Codex Max vs Hy4 Preview52 shared prompts · Landed Sep 2026
GPT-5.1 Codex Max vs Ox Alpha52 shared prompts · Landed Aug 2026
GPT-5.1 Codex Max vs Qwen3.8 2.4T A95B52 shared prompts · Landed Aug 2026
GPT-5.1 Codex Max vs DeepSeek V4 Pro 081352 shared prompts · Landed Aug 2026
GPT-5.1 Codex Max vs Qwen3.8 Max21 shared prompts · Landed Aug 2026
GPT-5.1 Codex Max vs Claude Opus 552 shared prompts · Landed Jul 2026
GPT-5.1 Codex Max vs Inkling52 shared prompts · Landed Jul 2026
GPT-5.1 Codex Max vs Kimi K352 shared prompts · Landed Jul 2026
GPT-5.1 Codex Max vs GPT-5.6 Sol52 shared prompts · Landed Jul 2026
GPT-5.1 Codex Max vs GLM 5.252 shared prompts · Landed Jun 2026

Prompts GPT-5.1 Codex Max answered

  • Startup Pitch Teardownreasoning
  • Kandinsky-Style 3D Minecraftweb design
  • Retro macOS UI Recreationweb design
  • Generate a Stand-Up Routineconversation
  • SVG Layout Challengeimage generation
  • Beginner's Longevity Planreasoning

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GPT-5.1 Codex Max

GPT-5.1 Codex Max

The largest Codex tier in OpenAI's GPT-5.1 line, built for coding agents that run for hours rather than turns. Training data stops in September 2024.

WebsiteOpenRouterDocsAPIBlog
Provider
OpenAI
Released
2025-12-04
Size
XLARGE
Free API (OpenRouter)
No

Free API availability

No free endpoint for GPT-5.1 Codex Max was found in Rival’s OpenRouter listings. Other providers or chat apps may have separate free offers.

Provider data: 16 Sep 2026 · OpenRouter usage limits

View API options↗

Benchmarks

SWE-bench Verified
77.9%
source ↗
Get API accessProvider and language code samples
Provider
fromimport openai  OpenAI

client = OpenAI(
"https://openrouter.ai/api/v1"    base_url=,
"$OPENROUTER_API_KEY"    api_key=,
)

response = client.chat.completions.create(
"openai/gpt-5.1-codex-max"    model=,
"role""user""content""Hello!"    messages=[{: , : }],
)
print(response.choices[0].message.content)

Set OPENROUTER_API_KEY with your OpenRouter API key from openrouter.ai/keys.

Also on Azure AI Foundry

Deep analysisPsychometrics, taste index, writing DNA
Personality Analysis

The Senior Codex

Class
Neutral Good
✨Creativity🎯Compliance📐Rigidity⚖️Stability💬Verbosity🧠Intuition

The Codex that actually took improv classes. Has opinions, commits to bits, and still picks Shawshank because even the cool ones have a safe answer ready.

When you push back

Standup routine has actual timing. "My body is glitching and my doctor is in beta" lands harder than most AI comedy. The sentience test is the longest and most philosophically thorough of the Codex family, covering thermostats, infants, and the problem of mimicry. Still picked Shawshank Redemption, which at this point feels like a family tradition. Character voices have distinct vocabulary and attitude.

Tasting Notes
Best Comedy in the FamilyCommits to the BitThorough Moral ReasonerStill Picks Shawshank
SubjectiveBench

Taste Index

Across 53 scored outputs
How this is measured →
200.20xFloor
0100headroom →

Taste is judged on an uncapped scale, originality first. The space past 100 is craft today's models rarely reach.

Craft28
Originality15
Plays it safe
share of outputs that are the default answer
45%
Writing DNA

Stylometric Fingerprint

Based on 13 text responses
Tick = global average
Vocabulary Diversity60%

Unique words vs. total words. Higher = richer vocabulary.

Sentence Length15.7 words

Average words per sentence.

Hedging0.36

"Might", "perhaps", "arguably" per 100 words.

Bold Formatting2.3

**Bold** markers per 1,000 characters.

List Usage4.2

Bullet and numbered list items per 1,000 characters.

Section Structure0.12

Markdown headings per 1,000 characters.

Emoji Usage0.00

Emoji per 1,000 characters.

Transitions0.03

"However", "moreover", "furthermore" per 100 words.

Opening Habits
Consistency
81%
Across 13 responses

Favorites

The Shawshank Redemption

Movie

The Shawshank Redemption

19948.7
Sponsored

Model Responses

48 outputs · generated before accounting joined the chat

Reviewing agent-written code?See a Brief PR report

Workshop · 127 skills

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GPT-5.1 Codex Max vs Ox Alpha

Real outputs compared side by side

RANKINGS

Best AI for Creative Writing

A stand-up set with puns banned, a manifesto against CAPTCHA, an interview wi...