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  5. GPT-5.3-CodexvsNex-N2.5-Mini (free)
Updated Sep 2026

GPT-5.3-CodexvsNex-N2.5-Mini (free)

Nex-N2.5-Mini (free) is cheaper than GPT-5.3-Codex at $0/M vs $1.75/M input tokens.

GPT-5.3-Codex and Nex-N2.5-Mini (free) compared across 15 shared prompts
SpecGPT-5.3-CodexNex-N2.5-Mini (free)
Input price$1.75/M tokensFree
Output price$14/M tokensFree
Context window400K tokens262K tokens
WeightsClosed—
Free API (OpenRouter)NoYes (1 provider)
ReleasedFeb 2026Sep 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-5.3-Codex203 words
Recipe: “Weeknight Volcano Pasta” 🌋🍝 A cozy, spicy-savory pasta made from pantry staples in about 25 minutes. Ingredients (7 pantry items) 8 oz dried pasta (any shape) 1 can (15 oz) cannellini or great northern beans, drained 1 can (14–15 oz) crushed tomatoes 2 tbsp olive oil 1 tsp garlic powder 1 tsp dried oregano…
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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

Historical Counterfactual Analysis

If the transistor had been invented in 1920 instead of 1947, trace the likely technological, economic, and geopolitical implications through…

GPT-5.3-Codex785 words
Great counterfactual. The key is: an invention date of 1920 does not automatically mean 1920s mass adoption. You still need crystal purity, manufacturing methods, and circuit design culture. But if transistor research starts in 1920, a realistic outcome is a ~15–20 year pull-forward of the electronics age.
Read the full answer
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

Debug This Architecture

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

GPT-5.3-Codex1,188 words
Great prompt. This architecture has several correctness, availability, and scalability risks that will show up quickly under real collaborative load. Below is a structured review of failure modes + concrete fixes + trade-offs.
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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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Advanced Longevity Plan (Biohacker)

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

GPT-5.3-Codex485 words
Absolutely—great goal. Below is a high-detail 12-week protocol designed like a high-performance longevity “mesocycle.” I’ll keep it practical, measurable, and advanced—but still safe. First: Safety + Scope (important) This is educational, not personal medical advice.
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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-5.3-Codex1,360 words
Great prompt. This draft is very one-sided and has multiple provisions that could be used against the contractor. Quick note: I’m not a lawyer, and enforceability depends on jurisdiction. This is practical contract-risk spotting, not legal advice.
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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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Michelin Star Recipe Design

Design an innovative recipe for a multi-component dish worthy of a Michelin 3-star restaurant. The recipe should feature an unusual…

GPT-5.3-Codex970 words
Dish Concept: “Forest Tide” Koji-cured venison loin, glazed venison cheek, sea urchin royale, charred celeriac, blackcurrant–shiso gastrique, and buckwheat-cacao tuile Narrative This dish is built around a deliberate tension: deep, iron-rich game (forest) against sweet-briny sea urchin (tide).
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Nex-N2.5-Mini (free)1,368 words
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.
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Our Verdict
GPT-5.3-Codex
GPT-5.3-Codex
Nex-N2.5-Mini (free)
Nex-N2.5-Mini (free)Runner-up

Not enough votes to call it. On the specs, GPT-5.3-Codex has the edge: bigger model tier, bigger context window, major provider backing.

Too close to call
API pricing

Cost per 1M tokens

GPT-5.3-Codex
Input
$1.75
Output
$14.00
Nex-N2.5-Mini (free)
Input
$0.000
Output
$0.000
Where to run it

3 hosts

GPT-5.3-Codex2 hosts
HostInOutContextUptime
Azure AI Foundry$1.75 in·$14.00 out·400k·100% upOpenAI$1.75 in·$14.00 out·400k·100% 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-5.3-Codex is developed by OpenAI while Nex-N2.5-Mini (free) is developed by Nex AGI. GPT-5.3-Codex has a 400K 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-5.3-Codex 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-5.3-Codex costs $1.75/M input tokens and Nex-N2.5-Mini (free) costs $0/M input tokens. Nex-N2.5-Mini (free) is $1.75/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-5.3-Codex 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

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GPT-5.3-Codex53 outputs, specs and price
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