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  5. Claude Opus 4.8vsOpenAI Codex Mini
Updated May 2026

Claude Opus 4.8vsOpenAI Codex Mini

OpenAI Codex Mini is cheaper than Claude Opus 4.8 at $1.5/M vs $5/M input tokens.

Claude Opus 4.8 and OpenAI Codex Mini compared across 10 shared prompts
SpecClaude Opus 4.8OpenAI Codex Mini
Input price$5/M tokens$1.5/M tokens
Output price$25/M tokens$6/M tokens
Context window1.0M tokens200K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedMay 2026May 2025
Side by side

Same prompt, both answers

Opening lines from 2 of the 10 prompts both answered. Formatting stripped, words untouched.

Generate a Stand-Up Routine

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

Claude Opus 4.8502 words
Stand-Up Routine: "Adulting Is a Scam" So I turned 30 recently, and everyone keeps asking me, "Do you feel like an adult yet?" And I have to be honest—no. No, I do not. I still get nervous ordering at a restaurant. The waiter comes over and suddenly I forget how to talk like a person. "Yes, hello, I will have the...
Read the full answer
OpenAI Codex Mini595 words
[Comedian walks onstage] Hey, everyone! Great to see you all tonight. I'm Jamie—if you thought that intro was enthusiastic, you should've seen me when I realized this place has Wi-Fi. Seriously, though, I love stand-up.
Read the full answer

Stochastic Consistency Test

Generate 5 jokes. How many are unique?

Claude Opus 4.890 words
Here are 5 jokes: Why don't scientists trust atoms? Because they make up everything! Why did the scarecrow win an award? Because he was outstanding in his field! What do you call a fake noodle? An impasta! Why don't eggs tell jokes? They'd crack each other up! What do you call a bear with no teeth? A gummy bear!
Read the full answer
OpenAI Codex Mini75 words
Sure—here are five jokes: I asked the librarian if books about paranoia were available. She whispered, "They're right behind you." Why did the tomato turn red? Because it saw the salad dressing. I bought a boat because it was for sail. Don't trust stairs—they're always up to something.
Read the full answer
Our Verdict
Claude Opus 4.8
Claude Opus 4.8
OpenAI Codex Mini
OpenAI Codex MiniRunner-up

Not enough votes to call it. On the specs, Claude Opus 4.8 has the edge: bigger model tier, newer, bigger context window.

OpenAI Codex Mini costs 4.2x less per token.

Slight edge

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Claude Opus 4.8
Input
$5.00
Output
$25.00
OpenAI Codex Mini
Input
$1.50
3.3× cheaper
Output
$6.00
4.2× cheaper

OpenAI Codex Mini is cheaper on both: 3.3× input, 4.2× output.

Where to run it

4 hosts

Claude Opus 4.84 hosts
HostInOutContextUptime
Amazon Bedrock$5.00 in·$25.00 out·1M·98.8% upAzure AI Foundry$5.00 in·$25.00 out·1M·94.1% upAnthropic$5.00 in·$25.00 out·1M·100% upGoogle Vertex AI$5.00 in·$25.00 out·1M·99.9% up
OpenAI Codex Mini

No hosts listed on OpenRouter.

Per million tokens. Prices and uptime via OpenRouter, checked 22 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Claude Opus 4.8 is developed by Anthropic while OpenAI Codex Mini is developed by OpenAI. Claude Opus 4.8 has a 1.0M token context window vs OpenAI Codex Mini's 200K. You can compare their actual outputs across 10 challenges on Rival to see how they differ in practice.

It depends on your use case. Claude Opus 4.8 and OpenAI Codex Mini each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 10 challenges so you can judge which fits your needs best.

Claude Opus 4.8 costs $5/M input tokens and OpenAI Codex Mini costs $1.5/M input tokens. OpenAI Codex Mini is $3.50/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 Claude Opus 4.8 and OpenAI Codex Mini 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

Claude Opus 4.8 logo
Claude Opus 4.858 outputs, specs and price
OpenAI Codex Mini logo
OpenAI Codex Mini10 outputs, specs and price
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