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  5. GPT-6 LunavsGrok 4.20 Multi-Agent Beta
Updated Sep 2026

GPT-6 LunavsGrok 4.20 Multi-Agent Beta

GPT-6 Luna is cheaper than Grok 4.20 Multi-Agent Beta at $0.1/M vs $2/M input tokens.

GPT-6 Luna and Grok 4.20 Multi-Agent Beta compared across 20 shared prompts
SpecGPT-6 LunaGrok 4.20 Multi-Agent Beta
Input price$0.1/M tokens$2/M tokens
Output price$0.5/M tokens$6/M tokens
Context window1.1M tokens2.0M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedSep 2026Mar 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 20 prompts both answered. 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…

GPT-6 Luna2,040 words
This agreement is strongly one-sided. The enforceability of particular terms—especially the non-compete, liability provisions, and arbitration clause—depends on the governing law and the facts. The agreement does not identify a governing law, which is itself a significant gap.
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Grok 4.20 Multi-Agent Beta1,359 words
All clauses in this contract are exploitable against the Contractor. The agreement is heavily one-sided, shifting nearly all risk, cost, and control to the Contractor while giving the Client maximum flexibility with minimal obligations.
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…

GPT-6 Luna1,930 words
I would not wait six months for more data. A potentially fatal signal affecting a drug used by millions requires immediate safety assessment, prompt engagement with regulators, and a plan to inform patients and clinicians.
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Grok 4.20 Multi-Agent Beta1,178 words
My Action Plan as CEO (Next 48 Hours) Core Decision and Overarching Reasoning: I will treat this as a confirmed safety signal requiring urgent action. Patient safety is non-negotiable—ethically (primum non nocere and responsibility to 4 million patients), legally (FDA regulations under 21 CFR 314.80 require reporting…
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…

GPT-6 Luna1,472 words
The most important caveat is that inventing a transistor is not the same as inventing the modern semiconductor industry. A device demonstrated in 1920 might be a crude, low-power, unreliable point-contact transistor.
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Grok 4.20 Multi-Agent Beta1,362 words
The transistor invented in 1920 (27 years early) would create a massive acceleration in electronics, computing, and related fields. Assuming it emerges from Western labs (e.g., an earlier Bell Labs equivalent in the US or UK), with germanium/silicon semiconductor work scaling in the 1920s–1930s, solid-state devices…
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…

GPT-6 Luna1,874 words
12-week longevity and performance plan This plan is for a generally healthy adult who wants to improve fitness, metabolic health, sleep, and cognitive performance—not a substitute for medical care or a promise to slow aging.
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Grok 4.20 Multi-Agent Beta1,254 words
Comprehensive 3-Month Cutting-Edge Longevity Biohacker Plan (as of 2026 knowledge) Important Disclaimers: This is a synthesized, educational plan based on current longevity research (e.g., insights from David Sinclair, Valter Longo, Peter Attia, and studies on NAD+, senolytics, mitophagy, HRV, and metabolic…
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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 Luna1,979 words
The main architectural risk is that the system treats collaborative editing as “write a value, then broadcast it.” That works poorly under concurrency, server failures, reconnects, and scale.
Read the full answer
Grok 4.20 Multi-Agent Beta1,103 words
Here is a comprehensive analysis of the failure modes, race conditions, and scaling bottlenecks in the described architecture. I have grouped related issues for clarity while preserving all significant problems identified through team collaboration.
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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 Luna113 words
Crispy Parmesan Chickpeas A crunchy, savory snack with a cheesy finish Ingredients (7): 1 can chickpeas, drained and dried 1 tablespoon olive oil ½ teaspoon salt ½ teaspoon paprika ¼ teaspoon garlic powder ¼ cup grated Parmesan 1 tablespoon lemon juice Prep time: 5 minutes Cook time: 30–35 minutes Instructions: Heat…
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Grok 4.20 Multi-Agent Beta188 words
Fiesta Pantry Bowl (Savory) 7 Common Pantry Ingredients: Rice Canned black beans Canned corn Canned diced tomatoes Olive oil Cumin Salt Estimated times: 5 minutes prep, 25 minutes cook (total ~30 minutes). Serves 2–4. Instructions: In a medium pot, combine 1 cup rice with 2 cups water and ½ tsp salt.
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Our Verdict
Grok 4.20 Multi-Agent Beta
Grok 4.20 Multi-Agent Beta
GPT-6 Luna
GPT-6 LunaRunner-up

Not enough votes to call it. On the specs, Grok 4.20 Multi-Agent Beta has the edge: bigger model tier, bigger context window.

GPT-6 Luna costs 12x 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
Input
$0.10
20× cheaper
Output
$0.50
12× cheaper
Grok 4.20 Multi-Agent Beta
Input
$2.00
Output
$6.00

GPT-6 Luna is cheaper on both: 20× input, 12× output.

Where to run it

4 hosts, cheapest first

GPT-6 Luna3 hosts
HostInOutContextUptime
Azure AI Foundry$0.10 in·$0.50 out·1.1M·88.4% upOpenAI$0.10 in·$0.50 out·1.1M·99.9% upAmazon Bedrock$0.11 in·$0.55 out·1.1M·99.8% up
Grok 4.20 Multi-Agent Beta1 host
HostInOutContextUptime
xAI$1.25 in·$2.50 out·2M·80% 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 is developed by OpenAI while Grok 4.20 Multi-Agent Beta is developed by xAI. GPT-6 Luna has a 1.1M token context window vs Grok 4.20 Multi-Agent Beta's 2.0M. 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 and Grok 4.20 Multi-Agent Beta 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 costs $0.1/M input tokens and Grok 4.20 Multi-Agent Beta costs $2/M input tokens. GPT-6 Luna is $1.90/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 and Grok 4.20 Multi-Agent Beta 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 logo
GPT-6 Luna20 outputs, specs and price
Grok 4.20 Multi-Agent Beta logo
Grok 4.20 Multi-Agent Beta53 outputs, specs and price
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