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  5. Grok 4.1 FastvsLaguna XS 2.1 (free)
Updated Jul 2026

Grok 4.1 FastvsLaguna XS 2.1 (free)

Laguna XS 2.1 (free) is the newer model, released after Grok 4.1 Fast.

Grok 4.1 Fast and Laguna XS 2.1 (free) compared across 11 shared prompts
SpecGrok 4.1 FastLaguna XS 2.1 (free)
Input price—Free
Output price—Free
Context window—262K tokens
Free API (OpenRouter)NoYes (1 provider)
ReleasedNov 2025Jul 2026
Side by side

Same prompt, both answers

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

Historical Counterfactual Analysis

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

Grok 4.1 Fast922 words
Technological Implications Immediate Advancements (1920s-1930s): Transistors replace bulky, power-hungry vacuum tubes by mid-1920s. Radios become pocket-sized and cheap by 1925 (vs. 1954 historically), accelerating mass media.
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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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Adversarial Contract Review

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

Grok 4.1 Fast1,106 words
Analysis of Exploitable Clauses Below, I identify all nine clauses as potentially exploitable against the Contractor, explain the risks (how they could be abused), propose specific modifications to make the contract more balanced, and provide legal reasoning grounded in general principles of U.S.
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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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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…

Grok 4.1 Fast874 words
Explanation for the Experienced Software Engineer Think of a large language model (LLM) like GPT as an enormous, distributed autocomplete engine built on a transformer architecture—imagine a system where every API endpoint you've ever queried is distilled into a single, massively parallelizable service that handles…
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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…
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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…

Grok 4.1 Fast1,041 words
Lunar Tide Conceptual Narrative Lunar Tide captures the mesmerizing interplay between celestial forces and oceanic depths, where the moon's pale luminescence tugs at the sea's primordial pulse.
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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.
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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…

Grok 4.1 Fast659 words
Comprehensive 3-Month Longevity Biohacking Plan Introduction and Assumptions This plan is designed for an advanced biohacker (healthy adult, age 30-50, no major medical conditions) aiming to optimize longevity markers (e.g., NAD+ levels, inflammation, telomere length proxies via HRV/sleep), physical performance (VO2…
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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).
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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…

Grok 4.1 Fast555 words
1-Month Plan for Better Health and Longevity This beginner-friendly plan focuses on three foundational areas: Diet, Exercise, and Sleep. These pillars drive longevity by reducing inflammation, building resilience, and optimizing recovery. Commit to small, consistent changes—aim for 80% adherence.
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Laguna XS 2.1 (free)409 words
1-Month Health & Longevity Plan Focus Areas: Diet, Exercise, Sleep Week 1: Start with Foundational Habits Diet: Action: Add 1 serving of fruit or vegetables daily (e.g., a banana with breakfast, a side salad with lunch). Why: Boosts nutrient intake and fiber.
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Our Verdict
Grok 4.1 Fast
Grok 4.1 Fast
Laguna XS 2.1 (free)
Laguna XS 2.1 (free)Runner-up

Not enough votes to call it. On the specs, Grok 4.1 Fast has the edge: bigger model tier, major provider backing.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Grok 4.1 Fast
Input
—
Output
—
Laguna XS 2.1 (free)
Input
$0.000
Output
$0.000
Where to run it

1 host

Grok 4.1 Fast

No hosts listed on OpenRouter.

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 23 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Grok 4.1 Fast is developed by xAI while Laguna XS 2.1 (free) is developed by Poolside. You can compare their actual outputs across 11 challenges on Rival to see how they differ in practice.

It depends on your use case. Grok 4.1 Fast 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.

This page shows a side-by-side comparison of Grok 4.1 Fast 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

Grok 4.1 Fast logo
Grok 4.1 Fast59 outputs, specs and price
Laguna XS 2.1 (free) logo
Laguna XS 2.1 (free)11 outputs, specs and price
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