What is the difference between Claude Opus 5 and GPT-5.3-Codex?

Claude Opus 5 is developed by Anthropic while GPT-5.3-Codex is developed by OpenAI. Claude Opus 5 has a 1.0M token context window vs GPT-5.3-Codex's 400K. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

Which is better, Claude Opus 5 or GPT-5.3-Codex?

It depends on your use case. Claude Opus 5 and GPT-5.3-Codex each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 53 challenges so you can judge which fits your needs best.

How much does Claude Opus 5 cost compared to GPT-5.3-Codex?

Claude Opus 5 costs $5/M input tokens and GPT-5.3-Codex costs $1.75/M input tokens. GPT-5.3-Codex is $3.25/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

How can I compare Claude Opus 5 and GPT-5.3-Codex on Rival?

This page shows a side-by-side comparison of Claude Opus 5 and GPT-5.3-Codex 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 Claude Opus 5 and GPT-5.3-Codex?

Claude Opus 5 is developed by Anthropic while GPT-5.3-Codex is developed by OpenAI. Claude Opus 5 has a 1.0M token context window vs GPT-5.3-Codex's 400K. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

Which is better, Claude Opus 5 or GPT-5.3-Codex?

It depends on your use case. Claude Opus 5 and GPT-5.3-Codex each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 53 challenges so you can judge which fits your needs best.

How much does Claude Opus 5 cost compared to GPT-5.3-Codex?

Claude Opus 5 costs $5/M input tokens and GPT-5.3-Codex costs $1.75/M input tokens. GPT-5.3-Codex is $3.25/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

How can I compare Claude Opus 5 and GPT-5.3-Codex on Rival?

This page shows a side-by-side comparison of Claude Opus 5 and GPT-5.3-Codex 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.

Claude Opus 5 vs GPT-5.3-Codex: Which Is Better?

Updated Jul 2026

Our Verdict

Claude Opus 5

GPT-5.3-CodexRunner-up

No community votes yet. On paper, Claude Opus 5 has the edge — newer, bigger context window.

Too close to call

API pricing

Cost per 1M tokens

Claude Opus 5

Input

$5.00

Output

$25.00

GPT-5.3-Codex

Input

$1.75

2.9× cheaper

Output

$14.00

1.8× cheaper

GPT-5.3-Codex is cheaper on both — 2.9× input, 1.8× output

Writing DNA

Style Comparison

Similarity

33%

GPT-5.3-Codex uses 9.2x more emoji

Claude Opus 5

GPT-5.3-Codex

54%Vocabulary65%

21wSentence Length23w

0.40Hedging0.51

3.9Bold6.5

1.9Lists6.2

0.02Emoji0.16

0.71Headings1.90

0.05Transitions0.03

Based on 27 + 23 text responses

Research

What we learned reading every model

Claude Opus 5 and GPT-5.3-Codex 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-5.3-Codex vs MiniMax M3New provider

Claude Opus 5 vs Gemini 2.5 Pro Preview 06-05New provider

GPT-5.3-Codex vs Claude Opus 4Cross-provider

Updated Jul 2026

Our Verdict

Claude Opus 5

GPT-5.3-CodexRunner-up

No community votes yet. On paper, Claude Opus 5 has the edge — newer, bigger context window.

Too close to call

API pricing

Cost per 1M tokens

Claude Opus 5

Input

$5.00

Output

$25.00

GPT-5.3-Codex

Input

$1.75

2.9× cheaper

Output

$14.00

1.8× cheaper

GPT-5.3-Codex is cheaper on both — 2.9× input, 1.8× output

Writing DNA

Style Comparison

Similarity

33%

GPT-5.3-Codex uses 9.2x more emoji

Claude Opus 5

GPT-5.3-Codex

54%Vocabulary65%

21wSentence Length23w

0.40Hedging0.51

3.9Bold6.5

1.9Lists6.2

0.02Emoji0.16

0.71Headings1.90

0.05Transitions0.03

Based on 27 + 23 text responses

Research

What we learned reading every model

Claude Opus 5 and GPT-5.3-Codex 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-5.3-Codex vs MiniMax M3New provider

Claude Opus 5 vs Gemini 2.5 Pro Preview 06-05New provider

GPT-5.3-Codex vs Claude Opus 4Cross-provider