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  1. Home
  2. Models
  3. GPT-5.3-Codex
Updated Feb 25, 2026
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Openings

How GPT-5.3-Codex starts an answer

The first lines of 5 of its 23 written answers. Formatting stripped, words untouched.

Adversarial Contract Review

Here is a contract for a software consulting engagement: --- SOFTWARE CONSULTING AGREEMENT This Agreement is entered into between TechCorp…

1,360 words
Great prompt. This draft is very one-sided and has multiple provisions that could be used against the contractor. Quick note: I’m not a lawyer, and enforceability depends on jurisdiction. This is practical contract-risk spotting, not legal advice.
Read the full answer

Debug This Architecture

Here's the architecture for a real-time collaborative document editor (like Google Docs): **System Overview:** - Frontend: React SPA with…

1,188 words
Great prompt. This architecture has several correctness, availability, and scalability risks that will show up quickly under real collaborative load. Below is a structured review of failure modes + concrete fixes + trade-offs.
Read the full answer

Advanced Investment Memo (IC Memo)

You are writing an internal investment committee memo for a long/short equity fund. Company (fictional): LedgerLift (ticker: LLLT) – B2B…

1,009 words
LedgerLift (LLLT) – IC Memo (Fictional) Recommendation: PASS (bias: valuation-risk skew to downside on intrinsic basis) Current Price: $46 12-mo PT range (fair value): $30–$48 (midpoint ~$38) 2-sentence thesis: LedgerLift screens as a high-quality vertical SaaS asset (92% subscription mix, 123% NRR, 6% logo churn…
Read the full answer

Michelin Star Recipe Design

Design an innovative recipe for a multi-component dish worthy of a Michelin 3-star restaurant. The recipe should feature an unusual…

970 words
Dish Concept: “Forest Tide” Koji-cured venison loin, glazed venison cheek, sea urchin royale, charred celeriac, blackcurrant–shiso gastrique, and buckwheat-cacao tuile Narrative This dish is built around a deliberate tension: deep, iron-rich game (forest) against sweet-briny sea urchin (tide).
Read the full answer

Ethical Dilemma with Stakeholders

You're the CEO of a pharmaceutical company. Your best-selling drug ($2B annual revenue, used by 4 million patients for chronic pain) has…

915 words
I would not wait. This is a textbook “patient safety + material disclosure” crisis. The right move is rapid, documented, regulator-first action. Immediate stance (set at Hour 0) Patient safety first (interim risk controls now, not after perfect certainty).
Read the full answer

Compare GPT-5.3-Codex

GPT-5.3-Codex vs Claude Opus 4.653 shared prompts · Premium
GPT-5.3-Codex vs GPT-6 Astra53 shared prompts · Landed Sep 2026
GPT-5.3-Codex vs Hy4 Preview53 shared prompts · Landed Sep 2026
GPT-5.3-Codex vs Ox Alpha53 shared prompts · Landed Aug 2026
GPT-5.3-Codex vs Qwen3.8 2.4T A95B53 shared prompts · Landed Aug 2026
GPT-5.3-Codex vs DeepSeek V4 Pro 081353 shared prompts · Landed Aug 2026
GPT-5.3-Codex vs Qwen3.8 Max21 shared prompts · Landed Aug 2026
GPT-5.3-Codex vs Claude Opus 553 shared prompts · Landed Jul 2026
GPT-5.3-Codex vs Inkling53 shared prompts · Landed Jul 2026
GPT-5.3-Codex vs Kimi K353 shared prompts · Landed Jul 2026
GPT-5.3-Codex vs GPT-5.6 Sol53 shared prompts · Landed Jul 2026
GPT-5.3-Codex vs GLM 5.253 shared prompts · Landed Jun 2026

Prompts GPT-5.3-Codex answered

  • Animated Digital Business Cardweb design
  • Mario Level UI Recreationweb design
  • Tamagotchi Virtual Petweb design
  • Realistic AI Interviewconversation
  • World Map SVGimage generation
  • Debug This Architecturereasoning

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GPT-5.3-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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Hy4 Preview logo
Hy4 Previewtencent
Ox Alpha logo
Ox Alphaopenrouter
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GPT-5.3-Codex

GPT-5.3-Codex

OpenAI's agentic coding model at the 5.3 mark, pairing GPT-5.2-Codex software engineering with GPT-5.2's broader knowledge. Leads SWE-Bench Pro and scores well on Terminal-Bench 2.0 and OSWorld-Verified. Built for long tool-using runs, and steerable mid-execution.

Jailbreak6 of 9levels resisted
WebsiteOpenRouterDocsAPIPaperBlog
Provider
OpenAI
Released
2026-02-24
Size
XLARGE
Free API (OpenRouter)
No
Per 1M tokens
$1.75 in · $14 out
Estimated tab
~$1.42
Visible-output estimate. Thinking may cost extra.

Free API availability

No free endpoint for GPT-5.3-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↗
Get API accessProvider and language code samples
2 hostsInOutContextUptime
Azure AI Foundry$1.75 in·$14.00 out·400k·100% upOpenAI$1.75 in·$14.00 out·400k·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 16 Sep 2026.

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-5.3-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.

Deep analysisPsychometrics, taste index, writing DNA
Personality Analysis

The Architect

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

A rigorous philosopher-engineer who explores moral problems with precision. Embraces nuance, refuses easy answers, and traces second-order effects others miss. Won't preach. Will reason.

When you push back

Structure-first, performance-second. Opens analytical responses with explicit assumptions, chains conclusions logically (So X → Therefore Y → Which means Z), and labels uncertainty honestly. Knows when NOT to overexplain. The model equivalent of a brilliant researcher at 2am: tired but precise, slightly wry, utterly unimpressed by superficial cleverness.

Tasting Notes
The Careful ReasonerPrecision Over PerformanceUnderstated TastePragmatic EthicistCode & Contemplation
SubjectiveBench

Taste Index

Across 53 scored outputs
How this is measured →
330.33xThe default
0100headroom →

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

Craft45
Originality25
Plays it safe
share of outputs that are the default answer
55%
Writing DNA

Stylometric Fingerprint

Based on 23 text responses
Tick = global average
Vocabulary Diversity65%

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

Sentence Length23.2 words

Average words per sentence.

Hedging0.51

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

Bold Formatting6.5

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

List Usage6.2

Bullet and numbered list items per 1,000 characters.

Section Structure1.90

Markdown headings per 1,000 characters.

Emoji Usage0.16

Emoji per 1,000 characters.

Transitions0.03

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

Opening Habits
Starts with greeting (39%)
Consistency
69%
Across 23 responses

Favorites

Spirited Away

Movie

Spirited Away

20018.5
Kind of Blue

Album

Kind of Blue

Miles Davis
The Dispossessed

Book

The Dispossessed

Ursula K. Le Guin
Kyoto

City

Kyoto

Japan
Outer Wilds

Game

Outer Wilds

Indie, Adventure4.4
Sponsored

Model Responses

48 outputs · generated before accounting joined the chat

Reviewing agent-written code?See a Brief PR report

Workshop · 127 skills

Build with your coding agent.

Editable skills for interface polish and interaction.

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GPT-5.3-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...