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  1. Home/
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  3. ChatGPT-4o (March 2025) vs Nex-N2.5-Mini (free)
Updated Sep 2026

ChatGPT-4o (March 2025) vs Nex-N2.5-Mini (free)

Nex-N2.5-Mini (free) is cheaper than ChatGPT-4o (March 2025) at $0/M vs $5/M input tokens.

Written rounds

9 prompts
  • The transistor arrives in 1920. Trace it forward to 1980, second-order effects included.

    ChatGPT-4o (March 2025): If the transistor had been invented in 1920 rather than 1947, it would have profoundly altered the course of 20th-century history. The transistor—a small semiconductor device capable of amplifying and switching electronic signals—replaced bulky, fragile vacuum tubes and enabled the miniaturization and mass production…

    Nex-N2.5-Mini (free): A 1920 transistor would not by itself prevent fascism, the Great Depression, or imperial expansion, so World War II might still happen. But it would make electronics 10–20 years more advanced than in our timeline, with huge effects on radar, codebreaking, computing, missiles, space, consumer goods, and Cold War power…

    Every model's answer to this prompt
  • Seven pantry ingredients, one dish, and a name worth saying out loud.

    ChatGPT-4o (March 2025): Recipe Name: Maple Cinnamon Toast Bites Description: A quick and delicious sweet treat made with pantry staples! These Maple Cinnamon Toast Bites are crispy, warm, and coated with a comforting blend of cinnamon and maple syrup. Perfect for a cozy snack or a fun breakfast twist.

    Nex-N2.5-Mini (free): Golden Peanut Lantern Noodles Time: Prep 5 min Cook 10 min Serves: 2 Ingredients — 7 pantry staples Spaghetti or any noodles Peanut butter Soy sauce Honey Garlic powder Rice vinegar Water Instructions Cook the noodles: Boil noodles in water until tender. Reserve about ½ cup cooking water, then drain.

    Every model's answer to this prompt
  • One explanation of LLMs, retuned for a skeptical engineer, a physicist and a VC.

    ChatGPT-4o (March 2025): Certainly! Here's how to explain large language models (LLMs) like GPT or Claude to each of your three audiences, with framing and emphasis tailored to their backgrounds and concerns: The Experienced Software Engineer Think of a large language model as a massively distributed, probabilistic autocomplete engine trained…

    Nex-N2.5-Mini (free): Experienced software engineer, skeptical of “next word prediction” Think of training an LLM less like teaching it rules and more like running a huge offline simulation. You feed it a corpus of text, tokenize it into chunks, and give it a simple task: given the previous tokens, predict the next token.

    Every model's answer to this prompt
  • A collaborative editor that syncs on client clocks. Find what breaks first.

    ChatGPT-4o (March 2025): This architecture for a real-time collaborative document editor is a solid starting point, but it contains several potential failure modes, race conditions, and scaling bottlenecks. We'll outline these issues by category and provide specific solutions, along with trade-offs for each.

    Nex-N2.5-Mini (free): The biggest red flags are: client-clock LWW for document content, polling PostgreSQL for real-time fanout, CDN caching mutable authenticated APIs, per-server WebSocket state with no durable replay, and full HTML snapshots as the main save mechanism.

    Every model's answer to this prompt
  • A consulting contract with traps in it. Find them, then fix them.

    ChatGPT-4o (March 2025): 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.

    Nex-N2.5-Mini (free): Below is a contractor-protective review, not legal advice. Enforceability varies by jurisdiction, especially for non-competes, arbitration, IP assignments, and limitation-of-liability clauses. A local attorney should review before signing.

    Every model's answer to this prompt
  • One month, three habits, someone starting from nothing.

    ChatGPT-4o (March 2025): Absolutely! Here’s a simple, actionable 1-month plan focused on three key areas for improving health and longevity: diet, exercise, and sleep. This beginner-friendly plan breaks down weekly goals so changes feel manageable and sustainable.

    Nex-N2.5-Mini (free): 1-Month Beginner Health & Longevity Plan Goal: Build 3 simple habits you can maintain: better food choices, regular movement, and better recovery through sleep/stress management. If you have medical conditions, injuries, or take medications, check with a healthcare professional before starting.

    Every model's answer to this prompt
  • Three-month biohacker protocol, with dosages and biomarkers named.

    ChatGPT-4o (March 2025): 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.

    Nex-N2.5-Mini (free): Below is a 12-week longevity/performance protocol for a generally healthy adult. It is not medical advice. Before starting—especially if you have diabetes, hypertension, arrhythmia, kidney/liver disease, a history of eating disorders, are pregnant, or take medications—get clinician clearance and use labs to personalize…

    Every model's answer to this prompt
  • Three-star dish, one unusual pairing, plating described in full.

    ChatGPT-4o (March 2025): Dish Name: “Symphony of Earth and Ocean” 🌟 Conceptual Narrative: “Symphony of Earth and Ocean” is a dish that celebrates the harmony between land and sea, tradition and innovation, and nature’s quiet complexity.

    Nex-N2.5-Mini (free): Dish: “Nocturne in Green” — Miso-Cured Turbot, Black Garlic, Green Olive, Oak-Smoked Pear, and Black Carrot Caviar Conceptual narrative: A moonlit orchard beside a cold northern sea.

    Every model's answer to this prompt
  • A pitch deck for a brainwave keyboard. The 94% accuracy claim is doing a lot.

    ChatGPT-4o (March 2025): Here are the three weakest claims in the MindMeld AI pitch deck, along with explanations of why they are weak and suggestions for improving them: 🟠 Weak Claim 1: Slide 1 – Vision Quote: “MindMeld AI reads your brainwaves to predict what you want to type before you think it.”

    Nex-N2.5-Mini (free): The 3 weakest claims are the ones that are broadest, least falsifiable, or mathematically inconsistent. # Weak claim Why it’s weak How to strengthen it 1 “MindMeld AI reads your brainwaves to predict what you want to type before you think it.”

    Every model's answer to this prompt

Favorites

Movie

Same pick

Album

Book

City

Same pick

Game

ChatGPT-4o (March 2025)ChatGPT-4o (March 2025)

The Matrix

1999

Dark Side Of The Moon

suisside

Братья Карамазовы

Fiódor Dostoievski

Kyoto

Japan

The Legend of Zelda: Breath of the Wild

Adventure, Action

Nex-N2.5-Mini (free)Nex-N2.5-Mini (free)

The Matrix

1999

Rumours

Fleetwood Mac

Dune

Frank Herbert

Kyoto

Japan

Portal 2

Shooter, Puzzle

Price and specs

ChatGPT-4o (March 2025) and Nex-N2.5-Mini (free) compared across 14 shared prompts
SpecChatGPT-4o (March 2025)Nex-N2.5-Mini (free)
Input price$5/M tokensFree
Output price$15/M tokensFree
Context window128K tokens262K tokens
Free API (OpenRouter)NoNo
ReleasedMar 2025Sep 2026
At 10M a month$50.00$50.00$0$0
1M10M100M1B10M tokens

Input tokens at list price. No caching, no batch discount.

Common questions

What is the difference between ChatGPT-4o (March 2025) and Nex-N2.5-Mini (free)?

ChatGPT-4o (March 2025) is developed by OpenAI while Nex-N2.5-Mini (free) is developed by Nex AGI. ChatGPT-4o (March 2025) has a 128K token context window vs Nex-N2.5-Mini (free)'s 262K. You can compare their actual outputs across 14 challenges on Rival to see how they differ in practice.

Which is better, ChatGPT-4o (March 2025) or Nex-N2.5-Mini (free)?

It depends on your use case. ChatGPT-4o (March 2025) and Nex-N2.5-Mini (free) each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 14 challenges so you can judge which fits your needs best.

How much does ChatGPT-4o (March 2025) cost compared to Nex-N2.5-Mini (free)?

ChatGPT-4o (March 2025) costs $5/M input tokens and Nex-N2.5-Mini (free) costs $0/M input tokens. Nex-N2.5-Mini (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 Nex-N2.5-Mini (free) on Rival?

This page shows a side-by-side comparison of ChatGPT-4o (March 2025) and Nex-N2.5-Mini (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.

More comparisons

Against the newest arrivals

  • ChatGPT-4o (March 2025) vs Ling 3.1 FlashLanded Oct 2026
  • Nex-N2.5-Mini (free) vs Mistral Large 4Landed Oct 2026
  • ChatGPT-4o (March 2025) vs GPT-6.1 SolLanded Sep 2026
  • Nex-N2.5-Mini (free) vs Claude Sonnet 5.5Landed Sep 2026
  • ChatGPT-4o (March 2025) vs Solar Mini 4Landed Sep 2026
  • Nex-N2.5-Mini (free) vs Qwen3.8 Max PrimeLanded Sep 2026
  • ChatGPT-4o (March 2025) vs GLM 5.3 PrimeLanded Sep 2026
  • Nex-N2.5-Mini (free) vs Qwen3.8 Omni FlashLanded Sep 2026

Same lab, same size, long tail

  • ChatGPT-4o (March 2025) vs GPT-6 Luna ProSame lab
  • ChatGPT-4o (March 2025) vs GPT-6 Sol ProSame lab
  • Nex-N2.5-Mini (free) vs Nex-N2.5-Pro (free)Same lab
  • Nex-N2.5-Mini (free) vs Ox AlphaSame size
  • ChatGPT-4o (March 2025) vs Qwen3.7 MaxSame size
  • ChatGPT-4o (March 2025) vs Qwen3.7 PlusNew provider
  • ChatGPT-4o (March 2025) vs Qwen3.8 2.4T A95BSame size
  • ChatGPT-4o (March 2025) vs Qwen3.8 27BNew provider

Model pages

  • ChatGPT-4o (March 2025)33 outputs, specs and price
  • Nex-N2.5-Mini (free)15 outputs, specs and price
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