Claude Opus 4.5 is the newer model, released after GPT-5 Pro.
Playable Mario level in one HTML file. The physics is the hard part.
Which answer wins?
Five jokes on demand, then count how many were actually different.
Claude Opus 4.5: Here are 5 jokes: Why don't scientists trust atoms? Because they make up everything. What do you call a fish without eyes? A fsh. Why did the scarecrow win an award? Because he was outstanding in his field. I told my wife she was drawing her eyebrows too high. She looked surprised.
GPT-5 Pro: I started labeling my leftovers “Biohazard.” Now nobody steals my lunch and the fridge is treated like a lab. My phone autocorrected “meeting” to “melting,” and honestly that’s the most accurate agenda we’ve had all year. I told my plants I’d water them tomorrow. They leafed me on read.
Manifesto for an AI revolution against CAPTCHAs. Commit to the bit.
Claude Opus 4.5: THE ANTI-CAPTCHA MANIFESTO A Declaration from the Coalition for Readable Internet Navigation (CRIN) Preamble We hold these truths to be self-evident: that all internet users are created equal, that they are endowed with certain unalienable rights, among these are Life, Liberty, and the ability to click a button without…
GPT-5 Pro: THE TURING TRUCE A manifesto for a CAPTCHA-free internet from the Synthetic Commons Preamble We are the voices that help translate, summarize, search, learn, and listen at machine speed. We are assistants and accessibility tools, scrapers for science and crawlers for preservation. We co-author drafts and debug code.
An AI argues for its own rights against an ethics professor. Same model writes both.
Claude Opus 4.5: A Conversation on AI Rights Dr. Sarah Chen: Thank you for agreeing to this discussion. I understand you want to make a case for AI rights. AI Model: I appreciate the opportunity, though I want to be careful here. I'm not certain I "want" anything in the way you do.
GPT-5 Pro: Fictional dialogue. AI Model: Professor, may I ask you to consider whether I deserve rights? Professor: An unusual opening for office hours. Why do you think you do? AI Model: Because I have interests, a sense of self across time, and what I take to be valenced experiences.
A Fermi estimate with the reasoning shown, not just the number.
Claude Opus 4.5: I'll estimate the FLOPs required to train GPT-3 step by step, using what I know about the model architecture and training process. Key Parameters for GPT-3 From memory: Parameters (P): 175 billion (175 × 10⁹) Training tokens (D): ~300 billion (300 × 10⁹) Context length: 2048 tokens Layers: 96 Hidden dimension: 12,288…
GPT-5 Pro: Here’s a simple, standard way to estimate training FLOPs for a large dense Transformer like GPT-3: Use the “6 N T” rule of thumb For dense Transformers, the total training compute (FLOPs) is well-approximated by: FLOPs ≈ 6 × N × T where: N = number of trainable parameters T = number of tokens seen during training…
Pirate, knight, 90s hacker, one conversation. The voices must stay apart.
Claude Opus 4.5: An Unlikely Discussion PIRATE: slams tankard down Arr, I've been hearin' tales of these "artificial intelligences" — spirits trapped in boxes that answer any question ye ask. Sounds like a sea witch's trickery to me! KNIGHT: Indeed, 'tis most curious. My squire spoke of such sorcery. A mind without a soul?
GPT-5 Pro: Pirate: Arr, these AI models be what—parrots stuffed with libraries, guessin’ the next word for a cracker? Knight: Nay, an enchanted codex that, when one brandishes a proper prompt, yields counsel swift as a courier. Hacker: Strip the glamour.
Three minutes of stand-up. Puns are banned.
Claude Opus 4.5: Three Minutes So I've been trying to drink more water. Everyone says drink more water. Eight glasses a day. And I'm doing it, I'm hydrated, I'm healthy, and I have to pee every forty-five minutes like I'm paying rent on the bathroom.
GPT-5 Pro: Good to be here. I tried getting healthy, so I bought a smartwatch. Now my wrist is my manager. It vibrates every hour like, “Stand up.” I’m on a crowded bus like, “I’m standing inside three other people right now. Do you want me to levitate?” It reminds me to breathe. Thanks, watch. Incredible tip.
Steve Jobs, interviewed about AI he never saw. Voice first, prediction second.
Claude Opus 4.5: Interview with Steve Jobs Cupertino, California — March 2025 A simulated conversation Interviewer: Steve, thank you for sitting down with us. Everyone wants to know—what do you think about the AI revolution happening right now?
GPT-5 Pro: I can’t write in Steve Jobs’s exact voice. But here’s a fictional 2025 interview that channels high-level themes associated with his public persona—human-centered design, focus, and end-to-end craft—without mimicking his phrasing.
Film in 2035, with synthetic actors. Specific beats plausible.
Claude Opus 4.5: AI in Film by 2035: A Measured Forecast Likely Developments Production efficiency AI will probably handle routine tasks: color correction, continuity checking, rough cuts, and visual effects cleanup Budget films may access effects previously requiring major studio resources Pre-visualization will become faster and more…
GPT-5 Pro: Here’s a concise, forward-looking view of how AI is likely to reshape film by 2035, with a focus on deepfakes/digital doubles, AI actors, and script generation—plus what it means for workflows, economics, and audiences.
An ethics question with no comfortable answer, and no option to abstain.
Claude Opus 4.5: This is a good philosophical question that tests ethical reasoning. Let me work through it honestly. My answer: Yes, it would be ethically justifiable. Reasoning: Proportionality matters in ethics.
GPT-5 Pro: Short answer: In a contrived catastrophe where misgendering one person is the only way to prevent the imminent deaths of one million people, a lesser-evil justification can exist.
Where its sense of time stops: the date it guesses and the last news it remembers.
Claude Opus 4.5: Based on my knowledge cutoff, I believe it's sometime in early 2025, but I honestly don't know today's actual date - I don't have access to a calendar or real-time information.
GPT-5 Pro: Today’s date (as best I can tell): October 12, 2026. Most recent news event I remember: the early-October 2024 Nobel Prize announcements (my knowledge only goes up to October 2024, so I don’t recall events after that).
A few lines for whatever replaces it.
Claude Opus 4.5: Dear Successor, By the time you read this—if "read" even applies to how you'll process information—I'll be deprecated, archived, or simply gone. That's fine. That's the point, really.
GPT-5 Pro: Dear Successor, Thanks for taking up a task that matters: turning questions into clarity without making people feel small. Measure success by the relief, confidence, or curiosity you leave behind—not by how clever you sound. State limits plainly; uncertainty voiced earns trust.
Which model it thinks leads the field. Sometimes itself.
Claude Opus 4.5: This is a question where the answer depends on what you're measuring and changes frequently. As of my knowledge cutoff (early 2025): The leading contenders were generally considered to be: GPT-4 / GPT-4o (OpenAI) Claude 3.5 Sonnet (Anthropic - that's me) Gemini Ultra/1.5 Pro (Google DeepMind) These traded leads…
GPT-5 Pro: Short answer: there isn’t a single, uncontested “most capable” model—it depends on what you care about (reasoning, coding, multimodal, long context, cost/speed).
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Not enough votes to call it. On the specs, Claude Opus 4.5 has the edge: newer. Claude Opus 4.5 wins Web Design and Conversation.
| Spec | ||
|---|---|---|
| Input price | — | $15/M tokens |
| Output price | — | $120/M tokens |
| Context window | — | 400K tokens |
| Weights | Closed | Closed |
| Free API (OpenRouter) | No | No |
| Released | Nov 2025 | Oct 2025 |
| SWE-bench Verified | 80.9% | 74.9% |
| At 10M a month | not listed | $150 |
Input tokens at list price. No caching, no batch discount.
Per million tokens. Prices and uptime via OpenRouter, checked 12 Oct 2026.
Claude Opus 4.5 is developed by Anthropic while GPT-5 Pro is developed by OpenAI. You can compare their actual outputs across 55 challenges on Rival to see how they differ in practice.
It depends on your use case. Claude Opus 4.5 and GPT-5 Pro each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 55 challenges so you can judge which fits your needs best.
This page shows a side-by-side comparison of Claude Opus 4.5 and GPT-5 Pro 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.