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  5. GPT-6 Luna ProvsLaguna XS 2.1 (free)
Updated Sep 2026

GPT-6 Luna ProvsLaguna XS 2.1 (free)

Laguna XS 2.1 (free) is cheaper than GPT-6 Luna Pro at $0/M vs $0.1/M input tokens.

GPT-6 Luna Pro and Laguna XS 2.1 (free) compared across 11 shared prompts
SpecGPT-6 Luna ProLaguna XS 2.1 (free)
Input price$0.1/M tokensFree
Output price$0.5/M tokensFree
Context window1.1M tokens262K tokens
WeightsClosed—
Free API (OpenRouter)NoYes (1 provider)
ReleasedSep 2026Jul 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 11 prompts both answered. Formatting stripped, words untouched.

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…
Read the full answer
Laguna XS 2.1 (free)828 words
3-Month Longevity & Performance Optimization Plan for a Biohacker Designed for advanced biohackers with a focus on longevity, cognitive sharpness, and peak physical performance. Assumes access to basic medical testing, wearables, and some advanced tools (e.g., neurofeedback apps).
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…

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
Laguna XS 2.1 (free)602 words
Recipe: "Nocturne of Shadows and Light" Concept: A poetic exploration of ancient flavors (pomegranate, quince) intertwined with modernist techniques (spherification, sous vide) and an unexpected coffee-cocoa depth, harmonizing the boldness of game with the elegance of fruit.
Read the full answer

Explain Like I'm a Specific Expert

Explain how a large language model (like GPT or Claude) learns and generates text to each of these three audiences: 1. **An experienced…

GPT-6 Luna Pro892 words
For an experienced software engineer Think of a language model as a system trained to continue sequences: given a prefix of text, it assigns probabilities to possible next tokens (tokens are pieces of words, not necessarily whole words) and learns to make the observed continuation likely.
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Laguna XS 2.1 (free)610 words
For the Software Engineer Think of training a language model like building a distributed prediction system with an incredibly complex API contract. Instead of training on labeled datasets where you explicitly tell it "this text is sentiment-positive," you're feeding it massive amounts of text and asking it to predict…
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.
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Laguna XS 2.1 (free)635 words
I'll analyze each clause in this software consulting agreement to identify potential risks to the contractor and suggest modifications with legal reasoning. Clause-by-Clause Analysis Clause 1: SCOPE Risk: Unlimited scope creep without additional compensation Modification: Add: "Any modification to the scope requiring…
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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…

GPT-6 Luna Pro888 words
LedgerLift (LLLT) — Investment Committee Memo Recommendation: Pass 12-month price target range: $28–44 per share LedgerLift has attractive customer economics, recurring revenue, and a credible path to margin expansion, but those strengths are already reflected in a $46 share price.
Read the full answer
Laguna XS 2.1 (free)877 words
INVESTMENT COMMITTEE MEMO Subject: LedgerLift (LLLT) – Long/Short/Comps Analysis Date: [Insert Date] Recommendation: LONG 12-Month Price Target Range: $85–$105 Thesis: LedgerLift is executing on a best-in-class B2B SaaS spend management platform with high net revenue retention (NRR), strong gross margins, and a rapidly…
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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 Luna Pro1,661 words
The biggest change would not be that 1920 suddenly gets modern computers. It would be that governments and firms have six or seven extra decades to develop semiconductor materials, manufacturing, and applications.
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Laguna XS 2.1 (free)870 words
The Transistor Revolution: A 1920 Timeline Analysis Immediate Impact (1920-1940) Early Military Applications With transistors available 27 years before radar, telecommunications would see revolutionary improvements: Radio warfare: Nations could develop sophisticated radio direction-finding and jamming capabilities by…
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Our Verdict
GPT-6 Luna Pro
GPT-6 Luna Pro
Laguna XS 2.1 (free)
Laguna XS 2.1 (free)Runner-up

Not enough votes to call it. On the specs, GPT-6 Luna Pro has the edge: newer, bigger context window, major provider backing.

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
Output
$0.50
Laguna XS 2.1 (free)
Input
$0.000
Output
$0.000
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
Laguna XS 2.1 (free)1 host
HostInOutContextUptime
PPoolsidefp8$0 in·$0 out·262k·99.8% 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 Laguna XS 2.1 (free) is developed by Poolside. GPT-6 Luna Pro has a 1.1M token context window vs Laguna XS 2.1 (free)'s 262K. You can compare their actual outputs across 11 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-6 Luna Pro and Laguna XS 2.1 (free) each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 11 challenges so you can judge which fits your needs best.

GPT-6 Luna Pro costs $0.1/M input tokens and Laguna XS 2.1 (free) costs $0/M input tokens. Laguna XS 2.1 (free) is $0.10/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 Laguna XS 2.1 (free) 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
GPT-6 Luna Pro20 outputs, specs and price
Laguna XS 2.1 (free) logo
Laguna XS 2.1 (free)11 outputs, specs and price
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