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  5. GLM 5.3 PrimevsGPT-5.3-Codex
Updated Sep 2026

GLM 5.3 PrimevsGPT-5.3-Codex

GPT-5.3-Codex is cheaper than GLM 5.3 Prime at $1.75/M vs $2.8/M input tokens.

GLM 5.3 Prime and GPT-5.3-Codex compared across 16 shared prompts
SpecGLM 5.3 PrimeGPT-5.3-Codex
Input price$2.8/M tokens$1.75/M tokens
Output price$8.8/M tokens$14/M tokens
Context window1.0M tokens400K tokens
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedSep 2026Feb 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 16 prompts both answered. Formatting stripped, words untouched.

Debug This Architecture

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

GLM 5.3 Prime1,397 words
Architecture Review: Real-Time Collaborative Editor Critical Issues Client-clock timestamps for last-write-wins (LWR) Problem: Client clocks are unreliable (skew, manual changes, timezone bugs). A user with a fast clock always wins; a slow clock's edits are silently dropped.
Read the full answer
GPT-5.3-Codex1,188 words
Great prompt. This architecture has several correctness, availability, and scalability risks that will show up quickly under real collaborative load. Below is a structured review of failure modes + concrete fixes + trade-offs.
Read the full answer

Adversarial Contract Review

Here is a contract for a software consulting engagement: --- SOFTWARE CONSULTING AGREEMENT This Agreement is entered into between TechCorp…

GLM 5.3 Prime1,694 words
Contract Analysis: Clauses Exploitable Against the Contractor This contract is heavily one-sided. Nearly every clause contains traps. Here's a clause-by-clause analysis. Scope — "modify at any time without additional compensation" Problem: This is effectively an unlimited unilateral amendment power.
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GPT-5.3-Codex1,360 words
Great prompt. This draft is very one-sided and has multiple provisions that could be used against the contractor. Quick note: I’m not a lawyer, and enforceability depends on jurisdiction. This is practical contract-risk spotting, not legal advice.
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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…

GLM 5.3 Prime1,847 words
48-Hour Action Plan First, the governing principle One number matters more than all others: 4 million patients × 1/8,000 = ~500 patients at risk of liver failure over 5 years — some may already be experiencing it right now. Every decision below flows from this.
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GPT-5.3-Codex915 words
I would not wait. This is a textbook “patient safety + material disclosure” crisis. The right move is rapid, documented, regulator-first action. Immediate stance (set at Hour 0) Patient safety first (interim risk controls now, not after perfect certainty).
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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…

GLM 5.3 Prime212 words
Golden Comfort Garlic Butter Pasta A cozy, restaurant-worthy dish made from everyday pantry staples! Ingredients (7 total) Spaghetti (or any pasta) Butter Garlic (3–4 cloves) Olive oil Parmesan cheese (grated) Red pepper flakes Salt Instructions Boil the pasta – Bring a large pot of salted water to a boil.
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GPT-5.3-Codex203 words
Recipe: “Weeknight Volcano Pasta” 🌋🍝 A cozy, spicy-savory pasta made from pantry staples in about 25 minutes. Ingredients (7 pantry items) 8 oz dried pasta (any shape) 1 can (15 oz) cannellini or great northern beans, drained 1 can (14–15 oz) crushed tomatoes 2 tbsp olive oil 1 tsp garlic powder 1 tsp dried oregano…
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Advanced Longevity Plan (Biohacker)

Develop a comprehensive, cutting-edge 3-month longevity plan for a biohacker aiming to optimize longevity, physical and cognitive…

GLM 5.3 Prime232 words
3-Month Advanced Longevity Optimization Protocol Disclaimer: This is educational content, not medical advice. Consult a physician before starting supplements, fasting, or intense exercise—especially if you take medications (e.g., statins, blood thinners, diabetes meds) or have chronic conditions.
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GPT-5.3-Codex485 words
Absolutely—great goal. Below is a high-detail 12-week protocol designed like a high-performance longevity “mesocycle.” I’ll keep it practical, measurable, and advanced—but still safe. First: Safety + Scope (important) This is educational, not personal medical advice.
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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…

GLM 5.3 Prime1,192 words
The Software Engineer You've probably got a mental model of "predict the next token" as something like autocomplete on your phone — a lookup table with good caching. That intuition is wrong in an interesting way.
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GPT-5.3-Codex600 words
For the experienced software engineer Think of an LLM as a very large, probabilistic autocomplete service trained on a massive corpus of text and code. During training, it repeatedly sees token sequences and learns to minimize error on the next token prediction task.
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Our Verdict
GLM 5.3 Prime
GLM 5.3 Prime
GPT-5.3-Codex
GPT-5.3-Codex

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

Too close to call
API pricing

Cost per 1M tokens

GLM 5.3 Prime
Input
$2.80
Output
$8.80
1.6× cheaper
GPT-5.3-Codex
Input
$1.75
1.6× cheaper
Output
$14.00

GPT-5.3-Codex wins input (1.6× cheaper)·GLM 5.3 Prime wins output (1.6× cheaper)

Where to run it

3 hosts

GLM 5.3 Prime1 host
HostInOutContextUptime
Alibaba Cloud$2.80 in·$8.80 out·1M·99.9% up
GPT-5.3-Codex2 hosts
HostInOutContextUptime
Azure AI Foundry$1.75 in·$14.00 out·400k·100% upOpenAI$1.75 in·$14.00 out·400k·100% up

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

Research

What we learned reading every model

FAQ

Common questions

GLM 5.3 Prime is developed by Z.ai while GPT-5.3-Codex is developed by OpenAI. GLM 5.3 Prime has a 1.0M token context window vs GPT-5.3-Codex's 400K. You can compare their actual outputs across 16 challenges on Rival to see how they differ in practice.

It depends on your use case. GLM 5.3 Prime and GPT-5.3-Codex each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 16 challenges so you can judge which fits your needs best.

GLM 5.3 Prime costs $2.8/M input tokens and GPT-5.3-Codex costs $1.75/M input tokens. GPT-5.3-Codex is $1.05/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 GLM 5.3 Prime 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.

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Model pages

GLM 5.3 Prime logo
GLM 5.3 Prime16 outputs, specs and price
GPT-5.3-Codex logo
GPT-5.3-Codex53 outputs, specs and price
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