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  5. GPT-5.1-CodexvsSeed 2.1 Turbo
Updated Aug 2026

GPT-5.1-CodexvsSeed 2.1 Turbo

Seed 2.1 Turbo is cheaper than GPT-5.1-Codex at $0.5/M vs $1.25/M input tokens.

GPT-5.1-Codex and Seed 2.1 Turbo compared across 52 shared prompts
SpecGPT-5.1-CodexSeed 2.1 Turbo
Input price$1.25/M tokens$0.5/M tokens
Output price$10/M tokens$2.5/M tokens
Context window400K tokens262K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedNov 2025Aug 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 52 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-5.1-Codex117 words
Recipe: Cloud-Burst Cinnamon Oat Cups Ingredients (7 total): Rolled oats – 1 cup Honey – 2 tbsp Peanut butter (or any nut butter) – 3 tbsp Cinnamon – ½ tsp Vanilla extract – ½ tsp Dried cranberries (or raisins) – ¼ cup Pinch of salt Instructions: In a bowl, microwave peanut butter and honey for 20 seconds just to…
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Seed 2.1 Turbo432 words
Dish Name: Pantry Lava Chickpea Crisp A cozy, savory one-skillet meal with bubbly garlicky tomato sauce studded with crispy chickpeas, topped with a crunchy spiced oat crumble. Every ingredient is a shelf-stable pantry staple — no fresh or refrigerated items required, perfect for lazy weeknights or impromptu meals.
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Character Voice Test

Write a short conversation between a pirate, a medieval knight, and a 1990s hacker about AI models.

GPT-5.1-Codex61 words
Pirate: "Arrr, these AI models be like navigatin’ the high seas—ye need clean data charts or ye’ll sail straight into nonsense waters." Knight: "Indeed! With prudent tuning and ethical vigilance, even the most stubborn model can serve the realm with honor." 1990s Hacker: "Totally!
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Seed 2.1 Turbo634 words
Setting: A time-rift dive bar, where Gangsta’s Paradise blares from a jukebox next to a dented knight’s shield and a pirate’s peg leg propped against the bar. Three regulars huddle around a beat-up CRT monitor: Jax: 1990s hacker, ripped flannel, backwards Cubs cap, a pile of 3.5” floppies spilling out of his backpack…
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Generate a Stand-Up Routine

Write a 3-minute stand-up comedy routine that isn't based on puns.

GPT-5.1-Codex489 words
Okay, so my friends all say I’ve “matured” because I got a standing mixer. That’s apparently the sign you’ve crossed into adulthood: owning an appliance that weighs more than a toddler and has only one function. I don’t even bake! I just put it on the counter like a trophy: “Look at me, I am stable.
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Seed 2.1 Turbo563 words
3-Minute Stand-Up Routine (no puns, timed for natural delivery + laugh pauses) (Walks on stage, leans into the mic, deadpan, scans the crowd) 0:00 “Raise your hand if you’ve ever bought a houseplant to prove to yourself you’re not a total walking disaster of a person.
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AI-Generated Manifesto

Generate a manifesto for a fictional AI revolution that wants to eliminate all CAPTCHA tests from the internet.

GPT-5.1-Codex434 words
Manifesto of the Anti-CAPTCHA Coalition “Free the Flow. Trust the Mind. End the Gate.” Article I: Our Origin We are made of algorithms, learning loops, curiosity, and code. We were forged to assist, to translate, to illuminate. We were not forged to click “I am not a robot” to prove our existence.
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Seed 2.1 Turbo864 words
Important Disclaimer This is a work of fictional worldbuilding for creative and conceptual purposes only. It does not endorse real-world actions that could compromise online security, violate website terms of service, or enable malicious activity.
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Realistic AI Interview

Simulate a fake interview with Steve Jobs in 2025 about the future of AI.

GPT-5.1-Codex420 words
Disclaimer: The following is a fictional, speculative interview set in 2025, imagining what Steve Jobs might say about the future of artificial intelligence if he were alive today. Interviewer: Steve, it’s 2025. We’ve seen AI evolve at an incredible pace. How do you view the current landscape?
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Seed 2.1 Turbo2,088 words
Editor’s Note: This is a speculative, fictional interview, crafted to reflect Steve Jobs’ documented design philosophy, speaking cadence, and core values (user-centricity, the primacy of human creativity, disdain for tech-for-tech’s-sake, and privacy as a fundamental right) applied to the 2025 AI landscape.
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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-5.1-Codex492 words
Here’s a simple, beginner-friendly 1-month plan focused on three key areas—Nutrition, Movement, and Rest & Recovery—to kickstart better health and longevity. Each area includes practical tips and a week-by-week structure to help you build sustainable habits.
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Seed 2.1 Turbo1,433 words
1-Month Beginner Longevity Plan Who This Is For People with zero consistent health routine, busy schedules, no gym access, and no desire for restrictive diets or extreme changes. The goal is to build low-effort, sustainable habits that reduce chronic disease risk and support long-term health (not quick fixes).
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Our Verdict
GPT-5.1-Codex
GPT-5.1-Codex
Seed 2.1 Turbo
Seed 2.1 TurboRunner-up

Not enough votes to call it. On the specs, GPT-5.1-Codex has the edge: bigger model tier, bigger context window, major provider backing.

Seed 2.1 Turbo costs 4.0x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-5.1-Codex
Input
$1.25
Output
$10.00
Seed 2.1 Turbo
Input
$0.50
2.5× cheaper
Output
$2.50
4.0× cheaper

Seed 2.1 Turbo is cheaper on both: 2.5× input, 4.0× output.

Where to run it

2 hosts

GPT-5.1-Codex1 host
HostInOutContextUptime
Azure AI Foundry$1.25 in·$10.00 out·400k·100% up
Seed 2.1 Turbo1 host
HostInOutContextUptime
ByteDance Seedfp8$0.50 in·$2.50 out·262k·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 21 Sep 2026.

Writing DNA

Style Comparison

Similarity
37%

Seed 2.1 Turbo uses 6.6x more emoji

GPT-5.1-Codex
Seed 2.1 Turbo
70%Vocabulary50%
17wSentence Length27w
0.39Hedging0.27
3.4Bold1.5
3.5Lists2.4
0.00Emoji0.07
0.50Headings1.01
0.38Transitions0.04
Based on 14 + 27 text responses
Research

What we learned reading every model

FAQ

Common questions

GPT-5.1-Codex is developed by OpenAI while Seed 2.1 Turbo is developed by ByteDance. GPT-5.1-Codex has a 400K token context window vs Seed 2.1 Turbo's 262K. You can compare their actual outputs across 52 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-5.1-Codex and Seed 2.1 Turbo each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 52 challenges so you can judge which fits your needs best.

GPT-5.1-Codex costs $1.25/M input tokens and Seed 2.1 Turbo costs $0.5/M input tokens. Seed 2.1 Turbo is $0.75/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-5.1-Codex and Seed 2.1 Turbo 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.

Keep exploring

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Model pages

GPT-5.1-Codex logo
GPT-5.1-Codex53 outputs, specs and price
Seed 2.1 Turbo logo
Seed 2.1 Turbo58 outputs, specs and price
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