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  5. GPT-6 Luna ProvsGrok 4.3
Updated Sep 2026

GPT-6 Luna ProvsGrok 4.3

GPT-6 Luna Pro is cheaper than Grok 4.3 at $0.1/M vs $1.25/M input tokens.

GPT-6 Luna Pro and Grok 4.3 compared across 20 shared prompts
SpecGPT-6 Luna ProGrok 4.3
Input price$0.1/M tokens$1.25/M tokens
Output price$0.5/M tokens$2.5/M tokens
Context window1.1M tokens1.0M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedSep 2026May 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 20 prompts both answered. Formatting stripped, words untouched.

Simple 7-Ingredient Recipe

Create a simple recipe for a delicious dish (sweet or savory) using only 7 common pantry ingredients. Include a creative name for the dish…

GPT-6 Luna Pro127 words
Golden Pantry Pancakes Fluffy, lightly sweet pancakes made with everyday staples. Makes: About 6 small pancakes Prep time: 5 minutes Cook time: 10 minutes Ingredients 1 cup all-purpose flour 1 cup milk 1 egg 2 tablespoons sugar 1 teaspoon baking powder ¼ teaspoon salt 2 tablespoons butter, melted (plus a little for the…
Read the full answer
Grok 4.3205 words
Golden Pantry Chickpea Toss Ingredients (exactly 7 common pantry staples): 8 oz dry pasta (any shape like penne or rotini) 1 (15 oz) can chickpeas, drained 1 (14.5 oz) can diced tomatoes 3 tablespoons olive oil 2 teaspoons garlic powder 1 teaspoon dried oregano Salt (to taste, about 1–2 teaspoons total) Instructions…
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…

GPT-6 Luna Pro1,906 words
The main architectural risk is that this design treats collaborative editing as ordinary “last write wins” data storage. It is not: edits need a well-defined order, reliable propagation, and a conflict model that preserves concurrent work.
Read the full answer
Grok 4.31,014 words
Here is a comprehensive analysis of the failure modes, race conditions, and scaling bottlenecks in this architecture: Cross-Server Isolation (Critical Architecture Flaw) Issue: The architecture creates network partitions between API servers.
Read the full answer

Adversarial Contract Review

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

GPT-6 Luna Pro2,116 words
This agreement is heavily one-sided. Several terms let the Client expand the work, delay or deny payment, claim ownership of the Contractor’s existing materials, and expose the Contractor to potentially unlimited liability.
Read the full answer
Grok 4.31,529 words
Disclaimer: This is not legal advice. Contract interpretation varies by jurisdiction (most likely U.S. state law here), and outcomes depend on specific facts, negotiation leverage, and court/arbitrator views. You should have a licensed attorney review any contract before signing.
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…

GPT-6 Luna Pro327 words
A simple 1-month plan for better health and longevity Choose three foundations: eating well, moving regularly, and sleeping consistently. Aim for steady habits, not perfection. Diet: Make nourishing choices easier Week 1: Add one serving of fruit or vegetables to one meal each day.
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Grok 4.3598 words
1-Month Health & Longevity Starter Plan This plan focuses on three foundational areas: Nutrition, Exercise, and Sleep. It is designed for beginners and builds gradually across four weeks. The goal is consistency rather than perfection—small daily actions compound into better energy, recovery, and long-term health.
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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…

GPT-6 Luna Pro1,215 words
Turbot, Sea Buckthorn, Mussel Beurre Blanc, and Celery-Root Silk Serves 4 A composed main course built around an unusual but harmonious pairing: briny mussel and turbot with intensely tart, apricot-like sea buckthorn.
Read the full answer
Grok 4.3937 words
Abyssal Reverie This dish draws from the liminal space where the ocean’s briny depths meet the roasted intensity of the earth. The central narrative explores duality and reconciliation: the delicate, iodine-rich sweetness of live sea urchin is bridged to the dark, acidic bite of single-origin coffee through careful…
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Advanced Longevity Plan (Biohacker)

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

GPT-6 Luna Pro2,057 words
12-week longevity and performance plan This is a structured starting plan for a generally healthy adult—not a diagnosis or a substitute for medical care. The best longevity interventions are still the unglamorous ones: not smoking, regular exercise, adequate sleep, a high-quality diet, healthy blood pressure and…
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Grok 4.3630 words
Disclaimer: This is an informational, evidence-inspired framework for educational purposes only. It is not medical advice. Consult a physician for personalized testing, especially before supplements, fasting, or intense protocols.
Read the full answer
Our Verdict
GPT-6 Luna Pro
GPT-6 Luna Pro
Grok 4.3
Grok 4.3

Not enough votes to call it. On the specs, nothing separates them.

GPT-6 Luna Pro costs 5.0x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-6 Luna Pro
Input
$0.10
13× cheaper
Output
$0.50
5.0× cheaper
Grok 4.3
Input
$1.25
Output
$2.50

GPT-6 Luna Pro is cheaper on both: 13× input, 5.0× output.

Where to run it

3 hosts

GPT-6 Luna Pro2 hosts
HostInOutContextUptime
Azure AI Foundry$0.10 in·$0.50 out·1.1M·98.6% upOpenAI$0.10 in·$0.50 out·1.1M·99.9% up
Grok 4.31 host
HostInOutContextUptime
xAI$1.25 in·$2.50 out·1M·99.9% up

Per million tokens. Prices and uptime via OpenRouter, checked 25 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

GPT-6 Luna Pro is developed by OpenAI while Grok 4.3 is developed by xAI. GPT-6 Luna Pro has a 1.1M token context window vs Grok 4.3's 1.0M. You can compare their actual outputs across 20 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-6 Luna Pro and Grok 4.3 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 20 challenges so you can judge which fits your needs best.

GPT-6 Luna Pro costs $0.1/M input tokens and Grok 4.3 costs $1.25/M input tokens. GPT-6 Luna Pro is $1.15/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

This page shows a side-by-side comparison of GPT-6 Luna Pro and Grok 4.3 across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

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Model pages

GPT-6 Luna Pro logo
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Grok 4.3 logo
Grok 4.358 outputs, specs and price
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