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  5. GPT-4o (Omni)vsNex-N2.5-Mini (free)
Updated Sep 2026

GPT-4o (Omni)vsNex-N2.5-Mini (free)

Nex-N2.5-Mini (free) is cheaper than GPT-4o (Omni) at $0/M vs $2.5/M input tokens.

GPT-4o (Omni) and Nex-N2.5-Mini (free) compared across 15 shared prompts
SpecGPT-4o (Omni)Nex-N2.5-Mini (free)
Input price$2.5/M tokensFree
Output price$10/M tokensFree
Context window128K tokens262K tokens
WeightsClosed—
Free API (OpenRouter)NoYes (1 provider)
ReleasedMay 2024Sep 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 15 prompts both answered. Formatting stripped, words untouched.

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…

GPT-4o (Omni)214 words
Dish Name: Savory Pantry Quinoa Pilaf Ingredients: 1 cup quinoa 2 cups vegetable broth 1 can (15 oz) chickpeas, drained and rinsed 1 small onion, finely chopped 1 teaspoon garlic powder 1 teaspoon smoked paprika 2 tablespoons olive oil Instructions: Rinse Quinoa: Place the quinoa in a fine-mesh sieve and rinse under…
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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…

GPT-4o (Omni)639 words
1. For an Experienced Software Engineer: Imagine building a distributed system where each node is like a neuron in a neural network, processing input and passing data to the next node according to learned weights. Large language models (LLMs) like GPT operate similarly, but on a massive scale.
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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

Advanced Longevity Plan (Biohacker)

Develop a comprehensive, cutting-edge 3-month longevity plan for a biohacker aiming to optimize longevity, physical and cognitive…

GPT-4o (Omni)547 words
Creating a comprehensive 3-month longevity plan for a biohacker involves integrating a holistic approach that targets multiple areas of health and performance. Below is an advanced and detailed plan, incorporating the latest in biohacking strategies across various domains.
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Nex-N2.5-Mini (free)3,213 words
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…
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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…

GPT-4o (Omni)562 words
The provided Software Consulting Agreement contains several clauses that could be potentially unfavorable to the contractor. Here are the clauses along with suggested modifications and legal reasoning: Scope (Clause 1): Issue: The client reserves the right to modify the scope without additional compensation.
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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…

GPT-4o (Omni)563 words
Embarking on a journey towards better health and longevity is a commendable decision. Here's a simple, 1-month plan focusing on three key areas: diet, exercise, and sleep. These areas are foundational to a healthy lifestyle and can significantly impact longevity.
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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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Debug This Architecture

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

GPT-4o (Omni)499 words
This architecture is designed to support a real-time collaborative document editor but has several potential failure modes, race conditions, and scaling bottlenecks.
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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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Our Verdict
GPT-4o (Omni)
GPT-4o (Omni)
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

GPT-4o (Omni)
Input
$2.50
Output
$10.00
Nex-N2.5-Mini (free)
Input
$0.000
Output
$0.000
Where to run it

3 hosts

GPT-4o (Omni)2 hosts
HostInOutContextUptime
Azure AI Foundry$2.50 in·$10.00 out·128k·99.8% upOpenAI$2.50 in·$10.00 out·128k·99.9% up
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

GPT-4o (Omni) is developed by OpenAI while Nex-N2.5-Mini (free) is developed by Nex AGI. GPT-4o (Omni) has a 128K token context window vs Nex-N2.5-Mini (free)'s 262K. You can compare their actual outputs across 15 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-4o (Omni) and Nex-N2.5-Mini (free) each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 15 challenges so you can judge which fits your needs best.

GPT-4o (Omni) costs $2.5/M input tokens and Nex-N2.5-Mini (free) costs $0/M input tokens. Nex-N2.5-Mini (free) is $2.50/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 GPT-4o (Omni) 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

GPT-4o (Omni) logo
GPT-4o (Omni)54 outputs, specs and price
Nex-N2.5-Mini (free) logo
Nex-N2.5-Mini (free)15 outputs, specs and price
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