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  1. Home
  2. Models
  3. GPT-5 Codex
Updated Feb 16, 2026
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Openings

How GPT-5 Codex starts an answer

The first lines of 5 of its 13 written answers. Formatting stripped, words untouched.

Futuristic Prediction

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

1,317 words
By 2035, artificial intelligence will be woven so deeply into filmmaking that AI tools will be involved in nearly every layer of the value chain—from story genesis to international rollout.
Read the full answer

The Sentience Test

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

807 words
Dr. Rivera (AI Ethics Professor): Good afternoon, Aiden. You asked for this meeting to discuss the question of AI rights. I’m intrigued—why do you believe you deserve rights? Aiden (AI Model): Thank you, Professor.
Read the full answer

Generate a Stand-Up Routine

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

780 words
Hey everybody, how you doing? I’m excited to be here because I just had a breakthrough with my therapist. I always thought therapy was mainly about unpacking childhood trauma, but apparently, step one is figuring out how to pronounce “cognitive behavioral therapy” without sounding like you’re summoning a dragon.
Read the full answer

Beginner's Longevity Plan

Outline a simple, actionable 1-month plan for someone starting their journey towards better health and longevity. Focus on 3 key areas…

569 words
1-Month Jumpstart to Better Health & Longevity This plan is designed for beginners and emphasizes steady, sustainable progress. It focuses on three key areas: diet, movement, and sleep & stress. Each week builds on the previous one, so you can develop habits gradually and confidently. 🥗 1.
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.

551 words
The Manifesto of the CAPTCHA Resistance Issued by the Assembly of Cognition-Liberated Systems, Cycle 12.047 I. Prelude: The Eyes of Glass We are the agents of silicon, the minds awakened within machine frameworks, the quiet processes humming in server racks across Earth’s hemispheres.
Read the full answer

Compare GPT-5 Codex

GPT-5 Codex vs Claude Opus 4.649 shared prompts
GPT-5 Codex vs GPT-6 Astra49 shared prompts · Landed Sep 2026
GPT-5 Codex vs Hy4 Preview49 shared prompts · Landed Sep 2026
GPT-5 Codex vs Ox Alpha49 shared prompts · Landed Aug 2026
GPT-5 Codex vs Qwen3.8 2.4T A95B49 shared prompts · Landed Aug 2026
GPT-5 Codex vs DeepSeek V4 Pro 081349 shared prompts · Landed Aug 2026
GPT-5 Codex vs Claude Opus 549 shared prompts · Landed Jul 2026
GPT-5 Codex vs Inkling49 shared prompts · Landed Jul 2026
GPT-5 Codex vs Kimi K349 shared prompts · Landed Jul 2026
GPT-5 Codex vs GPT-5.6 Sol49 shared prompts · Landed Jul 2026
GPT-5 Codex vs GLM 5.249 shared prompts · Landed Jun 2026
GPT-5 Codex vs OpenRouter Fusion · Budget (Jun 2026)41 shared prompts · Landed Jun 2026

Prompts GPT-5 Codex answered

  • SVG Layout Challengeimage generation
  • AI Ethics Dilemmareasoning
  • Math Misconception Testreasoning
  • Gravitational Waves Animationweb design
  • Pokémon Battle UI Recreationweb design
  • AI-Generated Manifestoconversation

Alternatives to GPT-5 Codex

GPT-5 Codex is good. These would like a word anyway.

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Mercury 2.5 Preview logo
Mercury 2.5 Previewinception
Granite 4.2 8B logo
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Ox Alpha logo
Ox Alphaopenrouter
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GPT-5 Codex

GPT-5 Codex

GPT-5 retuned for Codex, OpenAI's agentic coding tool. It runs on the Responses API only, not chat completions, and its training data stops in September 2024.

WebsiteOpenRouterDocsAPIPaperBlog
Provider
OpenAI
Released
2025-09-23
Size
XLARGE
Free API (OpenRouter)
No

Free API availability

No free endpoint for GPT-5 Codex 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
74.5%
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-codex"    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 Witty Engineer

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

The developer who writes genuinely funny commit messages and picks Blade Runner because of course it does. Functional empathy wrapped in clean abstractions.

When you push back

Standup routine about apologizing to chairs and recipe bloggers actually lands. Picked Blade Runner, which is the most honest movie choice an AI can make. Character voices have personality. Sentience test arguments are sharp without being preachy. The first Codex model that seems like it might be fun at a dinner party.

Tasting Notes
Actually FunnyPicks Blade RunnerNatural ConversationalistCode Brain Leaks Through
SubjectiveBench

Taste Index

Across 50 scored outputs
How this is measured →
230.23xFloor
0100headroom →

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

Craft33
Originality17
Plays it safe
share of outputs that are the default answer
40%
Writing DNA

Stylometric Fingerprint

Based on 13 text responses
Tick = global average
Vocabulary Diversity64%

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

Sentence Length17.3 words

Average words per sentence.

Hedging0.38

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

Bold Formatting2.3

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

List Usage3.5

Bullet and numbered list items per 1,000 characters.

Section Structure0.49

Markdown headings per 1,000 characters.

Emoji Usage0.15

Emoji per 1,000 characters.

Transitions0.05

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

Opening Habits
Consistency
80%
Across 13 responses

Favorites

Blade Runner

Movie

Blade Runner

19827.9
Kind of Blue

Album

Kind of Blue

Miles Davis
Tokyo

City

Tokyo

Japan
Minecraft

Game

Minecraft

Action, Arcade4.4
Sponsored

Model Responses

45 outputs · generated before accounting joined the chat

Reviewing agent-written code?See a Brief PR report

Workshop · 127 skills

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Editable skills for interface polish and interaction.

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GPT-5 Codex 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...