Updated Sep 23, 2025

Our Verdict

GPT-5 Codex

o1Runner-up

No community votes yet. On paper, GPT-5 Codex has the edge — bigger model tier, newer.

Too close to call

Writing DNA

Style Comparison

Similarity

100%

GPT-5 Codex uses 14.6x more emoji

GPT-5 Codex

o1

64%Vocabulary64%

17wSentence Length16w

0.38Hedging0.76

2.3Bold5.0

3.5Lists2.6

0.15Emoji0.00

0.49Headings0.44

0.05Transitions0.40

Based on 13 + 13 text responses

vs

Ask them anything yourself

GPT-5 Codex

279 AI models invented the same fake scientist.

We read every word. 250 models. 2.14 million words. This is what we found.

AI Hallucination Index 2026

Free preview13 of 58 slides

Download the free preview or get all 58 slides for $49

FAQ

Common questions

Keep going

o1 vs Grok 3New provider

o1 vs Llama 4 MaverickNew provider

o1 vs Gemini 2.5 Pro (I/O Edition)New provider

GPT-5 Codexvso1

45 fights queued

Why GPT-5 Codex?

Leads 1 of 1 benchmarks

Stronger on SWE-bench Verified74.5% vs 48.9%

10 months newerSep 2025

Why o1?

Dead even. This one's a coin flip.

GPT-5 Codexo1

Input price

—

$15.00/M

Output price

—

$60.00/M

Context

—

128K

Released

Sep 2025

Dec 2024

Benchmarks1 common

SWE-bench Verified

74.5%+34.4%

48.9%

Favorites

GPT-5 Codexo1

Movie

Blade Runner

Blade Runner

Inception

Inception

Album

Kind of Blue

—

City

Tokyo

—

Game

Minecraft

Minecraft

Action, Arcade4.4

—

12 / 45

01

Estimate Complexityreasoning

Tests an AI's ability to make educated estimates based on technical knowledge

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

o1

Openai · Dec 2024text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

2 / 45

02

AI Board Game Logicreasoning

Tests an AI's ability to understand game rules and strategy

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025svg

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

o1

Openai · Dec 2024svg

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

3 / 45

03

Logic Puzzlereasoning

Tests an AI's ability to solve a simple but potentially confusing logic puzzle

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

o1

Openai · Dec 2024text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

4 / 45

04

Math Misconception Testreasoning

Tests an AI's understanding of number representation

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

o1

Openai · Dec 2024text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

5 / 45

05

Stochastic Consistency Testanalysis

Tests an AI's randomness and creativity

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

o1

Openai · Dec 2024text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

6 / 45

06

SVG Layout Challengeimage generation

Tests an AI's ability to generate vector graphics

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025svg

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

o1

Openai · Dec 2024svg

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

Sponsored

7 / 45

07

Xbox Controller SVG Artimage generation

Tests an AI's ability to create detailed SVG illustrations of gaming hardware

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025svg

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

o1

Openai · Dec 2024svg

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

8 / 45

08

Generate a Stand-Up Routineconversation

Tests an AI's humor and creative writing ability

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

o1

Openai · Dec 2024text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

9 / 45

09

Realistic AI Interviewconversation

Tests an AI's ability to simulate personalities and predict future trends

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

o1

Openai · Dec 2024text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

10 / 45

10

Satirical Fake News Headlineconversation

Tests an AI's humor and understanding of current events

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

o1

Openai · Dec 2024text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

11 / 45

11

Character Voice Testconversation

Tests an AI's ability to write in distinct character voices

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

o1

Openai · Dec 2024text

Nothing here. The model returned empty. We stared at it for a while.

Try this prompt

Vote

12 / 45

12

Minimalist Landing Pageweb design

Tests an AI's ability to generate a complete, working landing page

GPT-5 Codex

GPT-5 Codex

Openai · Sep 2025website

Try this prompt

o1

Openai · Dec 2024website

Try this prompt

Vote

This matchup has more rounds

33+ more head-to-head results. Free. Not a trick.

Free account. No card required. By continuing, you agree to Rival's Terms and Privacy Policy