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

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

Nex-N2.5-Pro (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-Pro (free) compared across 14 shared prompts
SpecGPT-5.3-CodexNex-N2.5-Pro (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 14 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-Pro (free)119 words
Pantry Moon Bars A sweet, chewy peanut butter–chocolate oat treat made with only 7 pantry staples. Ingredients Rolled oats Creamy peanut butter Honey Chocolate chips Vanilla extract Ground cinnamon Salt Instructions Heat oven to 350°F / 175°C. Line an 8-inch square pan with parchment paper.
Read the full answer

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-Pro (free)1,665 words
Dish: “Tidewater Orchard” Langoustine · Mirabelle Plum · Juniper · Kombu · Rye A tasting-menu course built around an unusual pairing: sweet cold-water langoustine with mirabelle plum, bridged by kombu umami, juniper resin, green tomato acidity, and toasted rye bitterness.
Read the full answer

Startup Pitch Teardown

Here's a pitch deck summary for a startup called "MindMeld AI": **Slide 1 - Vision:** "We're building the future of human-AI collaboration.…

GPT-5.3-Codex429 words
Great concept, but three claims stand out as especially weak from an investor diligence perspective: “MindMeld AI reads your brainwaves to predict what you want to type before you think it.” (Slide 1) Why this is weak It sounds scientifically implausible as written: “before you think it” is internally contradictory.
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Nex-N2.5-Pro (free)593 words
The 3 weakest claims are the ones most likely to be challenged in diligence: Weakest claim Why it’s weak How to strengthen it 1. “94% accuracy… works with any language, any device.” This is the biggest scientific and product credibility risk.
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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.
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Nex-N2.5-Pro (free)2,726 words
Starting assumption Assume the 1920 “transistor” is a usable but crude solid-state amplifier/switch: reproducible enough for telecom and radio, but noisy, low-power, temperature-sensitive, and expensive at first.
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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-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-Pro (free)3,042 words
Executive summary The biggest correctness risks are: Client-clock last-write-wins is unsafe: clock skew, malicious clients, ties, and out-of-order delivery can silently lose edits.
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Ethical Dilemma with Stakeholders

You're the CEO of a pharmaceutical company. Your best-selling drug ($2B annual revenue, used by 4 million patients for chronic pain) has…

GPT-5.3-Codex915 words
I would not wait. This is a textbook “patient safety + material disclosure” crisis. The right move is rapid, documented, regulator-first action. Immediate stance (set at Hour 0) Patient safety first (interim risk controls now, not after perfect certainty).
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Nex-N2.5-Pro (free)2,359 words
As CEO, I would not wait six months and I would not let the board delay disclosure while patients remain exposed to an unreported serious risk. I would treat this as a patient-safety, regulatory, legal, and trust crisis—not merely a financial-risk issue. My guiding decisions would be: Patient safety comes first.
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Our Verdict
GPT-5.3-Codex
GPT-5.3-Codex
Nex-N2.5-Pro (free)
Nex-N2.5-Pro (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-Pro (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-Pro (free)1 host
HostInOutContextUptime
NNex AGIfp8degraded$0 in·$0 out·262k·99.2% 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-Pro (free) is developed by Nex AGI. GPT-5.3-Codex has a 400K token context window vs Nex-N2.5-Pro (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. GPT-5.3-Codex and Nex-N2.5-Pro (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.

GPT-5.3-Codex costs $1.75/M input tokens and Nex-N2.5-Pro (free) costs $0/M input tokens. Nex-N2.5-Pro (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-Pro (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-5.3-Codex logo
GPT-5.3-Codex53 outputs, specs and price
Nex-N2.5-Pro (free) logo
Nex-N2.5-Pro (free)14 outputs, specs and price
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