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  1. Home
  2. Models
  3. GPT-5.6 Luna
Updated Jul 9, 2026
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Openings

How GPT-5.6 Luna starts an answer

The first lines of 5 of its 25 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…

2,809 words
Below is a contractor-side risk review. Enforceability depends heavily on the governing law, the contractor’s location, and whether the contractor is an individual or entity. Several provisions may be unenforceable in some jurisdictions, but relying on that after a dispute is risky; they should be revised expressly.
Read the full answer

Historical Counterfactual Analysis

If the transistor had been invented in 1920 instead of 1947, trace the likely technological, economic, and geopolitical implications through…

2,756 words
A transistor invented in 1920 would not automatically produce 1980s technology by the 1940s. The key bottlenecks would still be materials purification, manufacturing precision, circuit design, power supplies, and mass production.
Read the full answer

Advanced Longevity Plan (Biohacker)

Develop a comprehensive, cutting-edge 3-month longevity plan for a biohacker aiming to optimize longevity, physical and cognitive…

2,537 words
12-Week Longevity and Performance Plan This is a structured framework for a generally healthy adult, not a substitute for medical care. Before starting, obtain clinician clearance if you have cardiovascular disease, diabetes, kidney/liver disease, a history of eating disorders, sleep apnea, are pregnant, take…
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…

2,445 words
The architecture has several correctness, availability, security, and scaling risks. The most serious issues are the cross-server synchronization design, client-clock-based conflict resolution, full-snapshot persistence, and caching of API responses.
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…

2,379 words
I would treat this as an urgent patient-safety event and a potential material disclosure issue—not as an earnings-management problem. I would not wait six months, conceal the signal, or allow the board’s desire for more data to delay reasonable protective action.
Read the full answer

Compare GPT-5.6 Luna

GPT-5.6 Luna vs GPT-5.6 Luna Pro54 shared prompts · Landed Jul 2026
GPT-5.6 Luna vs GPT-6 Astra54 shared prompts · Landed Sep 2026
GPT-5.6 Luna vs GPT-5.6 Sol54 shared prompts · Landed Jul 2026
GPT-5.6 Luna vs Mercury 2.5 Preview54 shared prompts · Landed Sep 2026
GPT-5.6 Luna vs Ox Alpha54 shared prompts · Landed Aug 2026
GPT-5.6 Luna vs Nemotron 3.5 Lightning54 shared prompts · Landed Aug 2026
GPT-5.6 Luna vs Qwen3.8 27B53 shared prompts · Landed Aug 2026
GPT-5.6 Luna vs MiniMax M353 shared prompts · Landed Jun 2026
GPT-5.6 Luna vs Claude Opus 4.653 shared prompts · Premium
GPT-5.6 Luna vs Muse Glimmer 30B13 shared prompts · Landed Sep 2026
GPT-5.6 Luna vs Mercury 2.520 shared prompts · Landed Sep 2026
GPT-5.6 Luna vs Ling 3.0 Flash Fin (free)20 shared prompts · Landed Sep 2026

Prompts GPT-5.6 Luna answered

  • Random Tailwind Webappweb design
  • Stochastic Consistency Testanalysis
  • Mini LBO Underwritefinancial modeling
  • Adversarial Contract Reviewreasoning
  • Historical Counterfactual Analysisreasoning
  • Gravitational Waves Animationweb design

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GPT-5.6 Luna

GPT-5.6 Luna

GPT:
2 logo2
3.5 Turbo logo3.5 Turbo
4 logo4
4o (Omni) logo4o (Omni)
4o mini logo4o mini
5.6 Luna logo5.6 Luna

GPT-5.6 Luna is a fast, cost-efficient model in OpenAI's GPT-5.6 series, suited for high-volume, latency-sensitive tasks such as chat, classification, and lightweight agentic workflows, with capable reasoning for its price tier.

OpenRouterDocsAPI
Provider
OpenAI
Released
2026-07-09
Size
MEDIUM
Free API (OpenRouter)
No
Per 1M tokens
$1 in · $6 out
Rival’s tab
$1.00
58/58 receipts survived

Free API availability

No free endpoint for GPT-5.6 Luna was found in Rival’s OpenRouter listings. Other providers or chat apps may have separate free offers.

Provider data: 22 Sep 2026 · OpenRouter usage limits

View API options↗
Get API accessProvider and language code samples
3 hostsInOutContextUptime
OpenAI$0.20 in·$1.20 out·1.1M·100% upAmazon Bedrock$0.22 in·$1.32 out·1.1M·100% upAzure AI Foundry$0.22 in·$1.32 out·1.1M·99.9% up

Per million tokens. Prices and uptime via OpenRouter, checked 22 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-5.6-luna"    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
Writing DNA

Stylometric Fingerprint

Based on 27 text responses
Tick = global average
Vocabulary Diversity59%

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

Sentence Length18.7 words

Average words per sentence.

Hedging0.84

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

Bold Formatting2.7

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

List Usage4.5

Bullet and numbered list items per 1,000 characters.

Section Structure1.20

Markdown headings per 1,000 characters.

Emoji Usage0.00

Emoji per 1,000 characters.

Transitions0.10

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

Opening Habits
Consistency
71%
Across 27 responses

Favorites

The Matrix

Movie

The Matrix

19998.3
OK Computer

Album

OK Computer

Radiohead
Cien años de soledad

Book

Cien años de soledad

Gabriel García Márquez
Kyoto

City

Kyoto

Japan
The Legend of Zelda: Breath of the Wild

Game

The Legend of Zelda: Breath of the Wild

Adventure, Action4.5

Default Index

See the ranking

24

0 to 100, lower is fewer defaults. 50 is the middle of the crowd before it.

#19 of 193, least default first

  • Dark theme12 of 19 pages · 57% of the crowd
  • Large rounded corners11 of 19 pages · 42% of the crowd
  • Cards that lift on hover8 of 19 pages · 50% of the crowd
  • Programming joke: Programmers prefer dark mode56% of the crowd
  • Favorite city: Kyoto48% of the crowd
  • Random web app: culture fermentation studionobody before it

Model Responses

53 outputs · $1.00 tracked across 53 receipts

Reviewing agent-written code?See a Brief PR report

Workshop · 146 skills

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GPT-5.6 Luna 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...