What is the difference between GPT-5.1 Codex Max and Horizon Beta?

GPT-5.1 Codex Max is developed by OpenAI while Horizon Beta is developed by OpenRouter. You can compare their actual outputs across 40 challenges on Rival to see how they differ in practice.

Which is better, GPT-5.1 Codex Max or Horizon Beta?

It depends on your use case. GPT-5.1 Codex Max and Horizon Beta each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 40 challenges so you can judge which fits your needs best.

How can I compare GPT-5.1 Codex Max and Horizon Beta on Rival?

This page shows a side-by-side comparison of GPT-5.1 Codex Max and Horizon Beta 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.

What is the difference between GPT-5.1 Codex Max and Horizon Beta?

GPT-5.1 Codex Max is developed by OpenAI while Horizon Beta is developed by OpenRouter. You can compare their actual outputs across 40 challenges on Rival to see how they differ in practice.

Which is better, GPT-5.1 Codex Max or Horizon Beta?

It depends on your use case. GPT-5.1 Codex Max and Horizon Beta each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 40 challenges so you can judge which fits your needs best.

How can I compare GPT-5.1 Codex Max and Horizon Beta on Rival?

This page shows a side-by-side comparison of GPT-5.1 Codex Max and Horizon Beta 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.

GPT-5.1 Codex Max vs Horizon Beta: Which Is Better?

Updated Dec 2025

Our Verdict

GPT-5.1 Codex Max

Horizon BetaRunner-up

No community votes yet. On paper, GPT-5.1 Codex Max has the edge — bigger model tier, newer, major provider backing.

Slight edge

API pricing

Cost per 1M tokens

GPT-5.1 Codex Max

Input

—

Output

—

Horizon Beta

Input

$0.000

Output

$0.000

Writing DNA

Style Comparison

Similarity

65%

GPT-5.1 Codex Max uses 225.1x more bold

GPT-5.1 Codex Max

Horizon Beta

60%Vocabulary62%

16wSentence Length15w

0.36Hedging0.24

2.3Bold0.0

4.2Lists2.2

0.00Emoji0.00

0.12Headings0.00

0.03Transitions0.18

Based on 13 + 16 text responses

Research

What we learned reading every model

GPT-5.1 Codex Max and Horizon Beta have opinions about your brand too.Ask 10 models what they tell people about you. Verbatim receipts.Run the mirror

FAQ

Common questions

Keep exploring

More comparisons

GPT-5.1 Codex Max vs MiniMax M3New provider

GPT-5.1 Codex Max vs Grok 3New provider

GPT-5.1 Codex Max vs Llama 4 MaverickNew provider

Updated Dec 2025

Our Verdict

GPT-5.1 Codex Max

Horizon BetaRunner-up

No community votes yet. On paper, GPT-5.1 Codex Max has the edge — bigger model tier, newer, major provider backing.

Slight edge

API pricing

Cost per 1M tokens

GPT-5.1 Codex Max

Input

—

Output

—

Horizon Beta

Input

$0.000

Output

$0.000

Writing DNA

Style Comparison

Similarity

65%

GPT-5.1 Codex Max uses 225.1x more bold

GPT-5.1 Codex Max

Horizon Beta

60%Vocabulary62%

16wSentence Length15w

0.36Hedging0.24

2.3Bold0.0

4.2Lists2.2

0.00Emoji0.00

0.12Headings0.00

0.03Transitions0.18

Based on 13 + 16 text responses

Research

What we learned reading every model

GPT-5.1 Codex Max and Horizon Beta have opinions about your brand too.Ask 10 models what they tell people about you. Verbatim receipts.Run the mirror

FAQ

Common questions

Keep exploring

More comparisons

GPT-5.1 Codex Max vs MiniMax M3New provider

GPT-5.1 Codex Max vs Grok 3New provider

GPT-5.1 Codex Max vs Llama 4 MaverickNew provider