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

Grok 4.1 FastvsLaguna S 2.1 (free)

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

Grok 4.1 Fast and Laguna S 2.1 (free) compared across 10 shared prompts
SpecGrok 4.1 FastLaguna S 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 3 of the 10 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…

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…
Read the full answer
Laguna S 2.1 (free)1,140 words
Comprehensive 3-Month Longevity Optimization Plan Phase 1: Foundation & Assessment (Month 1) Week 1-2: Baseline Establishment Comprehensive Health Testing Complete blood panel (CBC, CMP, lipid panel, inflammatory markers: hs-CRP, IL-6) Hormone panel (testosterone, estrogen, DHEA, cortisol, thyroid panel) Genetic…
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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 S 2.1 (free)275 words
I'll analyze each clause for potential exploitation against the contractor and suggest improvements. Exploitable Clauses & Recommended Modifications SCOPE CLAUSE Problem: "Client reserves the right to modify the scope at any time without additional compensation" Allows unlimited scope creep without extra pay No…
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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…

Grok 4.1 Fast768 words
LedgerLift (LLLT) Investment Committee Memo Recommendation: LONG 12-Mo PT Range: $55-70 Thesis LedgerLift is a best-in-class mid-market SaaS leader in spend management and AP automation, evidenced by category-leading NRR of 123%, sub-6% logo churn, and 18-month CAC payback.
Read the full answer
Laguna S 2.1 (free)910 words
INTERNAL INVESTMENT COMMITTEE MEMO 1. Recommendation & Thesis Recommendation: LONG 12-Month Price Target Range: $62 – $75/share Thesis: LedgerLift is a high-quality B2B SaaS platform with strong recurring revenue, exceptional unit economics, and durable customer retention.
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Our Verdict
Grok 4.1 Fast
Grok 4.1 Fast
Laguna S 2.1 (free)
Laguna S 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 S 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 S 2.1 (free)1 host
HostInOutContextUptime
PPoolsidefp4$0 in·$0 out·262k·100% 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 S 2.1 (free) is developed by Poolside. You can compare their actual outputs across 10 challenges on Rival to see how they differ in practice.

It depends on your use case. Grok 4.1 Fast and Laguna S 2.1 (free) each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 10 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 S 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 S 2.1 (free) logo
Laguna S 2.1 (free)10 outputs, specs and price
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