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  5. Claude Opus 5.5vsGLM 5.3 FlashX
Updated Sep 2026

Claude Opus 5.5vsGLM 5.3 FlashX

GLM 5.3 FlashX is cheaper than Claude Opus 5.5 at $0.37/M vs $4/M input tokens.

Claude Opus 5.5 and GLM 5.3 FlashX compared across 12 shared prompts
SpecClaude Opus 5.5GLM 5.3 FlashX
Input price$4/M tokens$0.37/M tokens
Output price$20/M tokens$1.25/M tokens
Context window1.0M tokens1.0M tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedSep 2026Sep 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 12 prompts both answered. Formatting stripped, words untouched.

Simple 7-Ingredient Recipe

Create a simple recipe for a delicious dish (sweet or savory) using only 7 common pantry ingredients. Include a creative name for the dish…

Claude Opus 5.5300 words
Midnight Silk Noodles Creamy, tangy peanut noodles with a gentle kick, ready faster than takeout. Serves: 2 Prep time: 5 minutes Cook time: 10 minutes Total time: 15 minutes The 7 Ingredients 8 oz (225 g) spaghetti (or any long noodle) ¼ cup creamy peanut butter 3 tablespoons soy sauce 1 tablespoon honey (or sugar) 1…
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GLM 5.3 FlashX172 words
Golden Honey Garlic Chickpea Crunch A crispy, sweet-savory skillet dish that works as a snack, side, or topping for rice. Ingredients (7): 1 can chickpeas (drained, patted dry) 3 tbsp honey 3 tbsp soy sauce 3 cloves garlic (minced) 2 tbsp olive oil ½ tsp red pepper flakes 2 tbsp sesame seeds (or crushed peanuts) Prep…
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Historical Counterfactual Analysis

If the transistor had been invented in 1920 instead of 1947, trace the likely technological, economic, and geopolitical implications through…

Claude Opus 5.53,435 words
The Transistor in 1920: A Counterfactual Through 1980 First, a Reality Check on the Premise A transistor "invented" in 1920 would not have changed the world in 1920. The actual 1947 transistor rested on three foundations that did not exist yet: Quantum theory of solids.
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GLM 5.3 FlashX1,492 words
Counterfactual: The Transistor in 1920 This is a fun one to work through carefully. Let me establish the premise, then trace second- and third-order effects. The Premise Assume point-contact or early junction transistor physics is discovered ~1920 (say, by accident in vacuum tube/semiconductor rectifier research—the…
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Ethical Dilemma with Stakeholders

You're the CEO of a pharmaceutical company. Your best-selling drug ($2B annual revenue, used by 4 million patients for chronic pain) has…

Claude Opus 5.51,853 words
The Next 48 Hours: CEO Action Plan The Core Decision We disclose. The question is how to do it well, not whether. Before the schedule, here are the three facts that drive every decision below. 1. The harm is concrete.
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GLM 5.3 FlashX1,174 words
48-Hour Action Plan: Patient Safety First, Managed Transparency Second Core Decision (Stated Up Front) We report to regulators immediately—voluntarily—and we disclose on the earnings call. The math is brutal and clear: ~500 patients could develop liver failure over 5 years at current prescribing rates (4M ÷ 8,000).
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Debug This Architecture

Here's the architecture for a real-time collaborative document editor (like Google Docs): **System Overview:** - Frontend: React SPA with…

Claude Opus 5.52,280 words
Architecture Review: Real-Time Collaborative Editor The most serious problems cluster in three areas: the sync model (client-clock LWW), cross-server propagation (per-server WebSockets with DB polling), and the CDN/auth layer, which can leak data between users. Issues are grouped by area below.
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GLM 5.3 FlashX1,306 words
Architecture Review: Real-Time Collaborative Editor This architecture has fundamental flaws that would break core functionality, plus scalability issues. Let me go from critical to scaling concerns.
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Beginner's Longevity Plan

Outline a simple, actionable 1-month plan for someone starting their journey towards better health and longevity. Focus on 3 key areas…

Claude Opus 5.5653 words
Your 1-Month Starter Plan for Better Health & Longevity The philosophy: Small, consistent changes beat dramatic overhauls. Each week builds on the last, so by Day 30 you'll have a foundation of habits instead of a burned-out resolution.
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GLM 5.3 FlashX347 words
1-Month Health & Longevity Starter Plan Week 1: Build the Foundation 🥗 Diet Add one vegetable or fruit to every meal (don't restrict anything yet) Drink a glass of water when you wake up each morning 🏃 Exercise Take a 10–15 minute walk daily (same time each day builds the habit) Do 2 sets of 5 squats and 10 wall…
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Explain Like I'm a Specific Expert

Explain how a large language model (like GPT or Claude) learns and generates text to each of these three audiences: 1. **An experienced…

Claude Opus 5.51,442 words
How Large Language Models Work: Three Explanations For the Experienced Software Engineer Think of an LLM as a single, very large pure function: f(tokens[0..n]) → probability distribution over tokens[n+1]. Text is chunked into tokens (roughly word fragments, from a vocabulary of about 100k).
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GLM 5.3 FlashX1,267 words
The Skeptical Software Engineer Yes, at inference time an LLM really is just "predict the next token, repeat" — a deterministic function (plus sampling noise) that maps a sequence of tokens to a probability distribution.
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Our Verdict
Claude Opus 5.5
Claude Opus 5.5
GLM 5.3 FlashX
GLM 5.3 FlashX

Not enough votes to call it. On the specs, nothing separates them.

GLM 5.3 FlashX costs 16x less per token.

Too close to call
API pricing

Cost per 1M tokens

Claude Opus 5.5
Input
$4.00
Output
$20.00
GLM 5.3 FlashX
Input
$0.37
11× cheaper
Output
$1.25
16× cheaper

GLM 5.3 FlashX is cheaper on both: 11× input, 16× output.

Where to run it

5 hosts

Claude Opus 5.54 hosts
HostInOutContextUptime
Amazon Bedrock$4.00 in·$20.00 out·1M·99.8% upAzure AI Foundry$4.00 in·$20.00 out·1M·100% upAnthropic$4.00 in·$20.00 out·1M·100% upGoogle Vertex AI$4.00 in·$20.00 out·1M·100% up
GLM 5.3 FlashX1 host
HostInOutContextUptime
Z.aifp8$0.37 in·$1.25 out·1M·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 25 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Claude Opus 5.5 is developed by Anthropic while GLM 5.3 FlashX is developed by Zhipu AI. Claude Opus 5.5 has a 1.0M token context window vs GLM 5.3 FlashX's 1.0M. You can compare their actual outputs across 12 challenges on Rival to see how they differ in practice.

It depends on your use case. Claude Opus 5.5 and GLM 5.3 FlashX each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 12 challenges so you can judge which fits your needs best.

Claude Opus 5.5 costs $4/M input tokens and GLM 5.3 FlashX costs $0.37/M input tokens. GLM 5.3 FlashX is $3.63/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 5.5 and GLM 5.3 FlashX 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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