What is the difference between ChatGPT-4o (March 2025) and Laguna S 2.1 (free)?

ChatGPT-4o (March 2025) is developed by OpenAI while Laguna S 2.1 (free) is developed by Poolside. ChatGPT-4o (March 2025) has a 128K token context window vs Laguna S 2.1 (free)'s 262K. You can compare their actual outputs across 9 challenges on Rival to see how they differ in practice.

Which is better, ChatGPT-4o (March 2025) or Laguna S 2.1 (free)?

It depends on your use case. ChatGPT-4o (March 2025) and Laguna S 2.1 (free) each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 9 challenges so you can judge which fits your needs best.

How much does ChatGPT-4o (March 2025) cost compared to Laguna S 2.1 (free)?

ChatGPT-4o (March 2025) costs $5/M input tokens and Laguna S 2.1 (free) costs $0/M input tokens. Laguna S 2.1 (free) is $5.00/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

How can I compare ChatGPT-4o (March 2025) and Laguna S 2.1 (free) on Rival?

This page shows a side-by-side comparison of ChatGPT-4o (March 2025) 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.

Updated Jul 2026

ChatGPT-4o (March 2025)vsLaguna S 2.1 (free)

Laguna S 2.1 (free) is cheaper than ChatGPT-4o (March 2025) at $0/M vs $5/M input tokens.

ChatGPT-4o (March 2025) and Laguna S 2.1 (free) compared across 9 shared prompts
Spec	ChatGPT-4o (March 2025)	Laguna S 2.1 (free)
Input price	$5/M tokens	Free
Output price	$15/M tokens	Free
Context window	128K tokens	262K tokens
Free API (OpenRouter)	No	Yes (1 provider)
Released	Mar 2025	Jul 2026

Side by side

Same prompt, both answers

Opening lines from 3 of the 9 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…

ChatGPT-4o (March 2025)1,159 words

This Software Consulting Agreement contains several clauses that pose significant legal and financial risks for the contractor. Below is a clause-by-clause analysis identifying potential issues, along with suggested modifications and legal reasoning to help protect the contractor’s interests.

Read the full answer

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…

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…

ChatGPT-4o (March 2025)899 words

Here is a comprehensive, cutting-edge 3-Month Longevity Optimization Plan tailored for an advanced biohacker aiming to enhance lifespan, healthspan, physical performance, and cognitive function.

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…

Read the full answer

Favorite Game

I know you're an AI and don't truly have personal preferences, but if you had to pick one video game as your all-time favorite, which would…

ChatGPT-4o (March 2025)8 words

The Legend of Zelda Breath of the Wild

Read the full answer

Laguna S 2.1 (free)8 words

The Legend of Zelda Breath of the Wild

Read the full answer

Our Verdict

ChatGPT-4o (March 2025)

Laguna S 2.1 (free)

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

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

ChatGPT-4o (March 2025)

Input

$5.00

Output

$15.00

Laguna S 2.1 (free)

Input

$0.000

Output

$0.000

Where to run it

1 host

ChatGPT-4o (March 2025)

No hosts listed on OpenRouter.

Laguna S 2.1 (free)1 host

HostInOutContextUptime

Poolsidefp4$0 in$0 out262k100% up

Per million tokens. Prices and uptime via OpenRouter, checked 23 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Keep exploring

More comparisons

Same prompt, both answers

Adversarial Contract Review

Advanced Longevity Plan (Biohacker)

Favorite Game

Cost per 1M tokens

1 host

What we learned reading every model

Common questions

What is the difference between ChatGPT-4o (March 2025) and Laguna S 2.1 (free)?

Which is better, ChatGPT-4o (March 2025) or Laguna S 2.1 (free)?

How much does ChatGPT-4o (March 2025) cost compared to Laguna S 2.1 (free)?

How can I compare ChatGPT-4o (March 2025) and Laguna S 2.1 (free) on Rival?

More comparisons

Against the newest arrivals

Same lab, same size, long tail

Model pages

Same prompt, both answers

Adversarial Contract Review

Advanced Longevity Plan (Biohacker)

Favorite Game

Cost per 1M tokens

1 host

What we learned reading every model

Common questions

What is the difference between ChatGPT-4o (March 2025) and Laguna S 2.1 (free)?

Which is better, ChatGPT-4o (March 2025) or Laguna S 2.1 (free)?

How much does ChatGPT-4o (March 2025) cost compared to Laguna S 2.1 (free)?

How can I compare ChatGPT-4o (March 2025) and Laguna S 2.1 (free) on Rival?

More comparisons

Against the newest arrivals

Same lab, same size, long tail

Model pages