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  5. ChatGPT-4o (March 2025)vsNex-N2.5-Mini (free)
Updated Sep 2026

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

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

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)NoYes (1 provider)
ReleasedMar 2025Sep 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 14 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…

ChatGPT-4o (March 2025)1,096 words
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…
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Nex-N2.5-Mini (free)2,076 words
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…
Read the full answer

Simple 7-Ingredient Recipe

Create a simple recipe for a delicious dish (sweet or savory) using only 7 common pantry ingredients. Include a creative name for the dish…

ChatGPT-4o (March 2025)265 words
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.
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Nex-N2.5-Mini (free)111 words
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.
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…

ChatGPT-4o (March 2025)704 words
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…
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Nex-N2.5-Mini (free)889 words
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.
Read the full answer

Debug This Architecture

Here's the architecture for a real-time collaborative document editor (like Google Docs): **System Overview:** - Frontend: React SPA with…

ChatGPT-4o (March 2025)876 words
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.
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Nex-N2.5-Mini (free)1,869 words
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.
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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…

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.
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Nex-N2.5-Mini (free)1,439 words
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.
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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…

ChatGPT-4o (March 2025)441 words
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.
Read the full answer
Nex-N2.5-Mini (free)671 words
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.
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Our Verdict
ChatGPT-4o (March 2025)
ChatGPT-4o (March 2025)
Nex-N2.5-Mini (free)
Nex-N2.5-Mini (free)

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

Too close to call
API pricing

Cost per 1M tokens

ChatGPT-4o (March 2025)
Input
$5.00
Output
$15.00
Nex-N2.5-Mini (free)
Input
$0.000
Output
$0.000
Where to run it

1 host

ChatGPT-4o (March 2025)

No hosts listed on OpenRouter.

Nex-N2.5-Mini (free)1 host
HostInOutContextUptime
NNex AGIbf16degraded$0 in·$0 out·262k·92.2% up

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

Research

What we learned reading every model

FAQ

Common questions

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.

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.

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.

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.

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Model pages

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