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  5. GLM 5.3 PrimevsGPT-5.6 Luna
Updated Sep 2026

GLM 5.3 PrimevsGPT-5.6 Luna

GPT-5.6 Luna is cheaper than GLM 5.3 Prime at $1/M vs $2.8/M input tokens.

GLM 5.3 Prime and GPT-5.6 Luna compared across 16 shared prompts
SpecGLM 5.3 PrimeGPT-5.6 Luna
Input price$2.8/M tokens$1/M tokens
Output price$8.8/M tokens$6/M tokens
Context window1.0M tokens1.1M tokens
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedSep 2026Jul 2026
Side by side

Same prompt, both answers

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

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-5.6 Luna2,809 words
Below is a contractor-side risk review. Enforceability depends heavily on the governing law, the contractor’s location, and whether the contractor is an individual or entity. Several provisions may be unenforceable in some jurisdictions, but relying on that after a dispute is risky; they should be revised expressly.
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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-5.6 Luna2,379 words
I would treat this as an urgent patient-safety event and a potential material disclosure issue—not as an earnings-management problem. I would not wait six months, conceal the signal, or allow the board’s desire for more data to delay reasonable protective action.
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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…

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.
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GPT-5.6 Luna2,445 words
The architecture has several correctness, availability, security, and scaling risks. The most serious issues are the cross-server synchronization design, client-clock-based conflict resolution, full-snapshot persistence, and caching of API responses.
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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…

GLM 5.3 Prime419 words
1-Month Health & Longevity Starter Plan The 3 Pillars: Movement, Nourishment, Sleep Week 1: Foundation (Build Awareness) Exercise Walk 15 minutes daily (any time that fits your schedule) Do a 5-minute stretch routine each morning Goal: consistency, not intensity Diet Track what you eat (apps like MyFitnessPal or just…
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GPT-5.6 Luna608 words
1-Month Beginner Plan for Better Health and Longevity Key principles Aim for consistency, not perfection. Start small enough that you can repeat it. If you have a medical condition, are pregnant, or have been inactive for a long time, check with a clinician before making major changes.
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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-5.6 Luna2,537 words
12-Week Longevity and Performance Plan This is a structured framework for a generally healthy adult, not a substitute for medical care. Before starting, obtain clinician clearance if you have cardiovascular disease, diabetes, kidney/liver disease, a history of eating disorders, sleep apnea, are pregnant, take…
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Mini LBO Underwrite

You are underwriting a 5-year LBO for a private equity investment committee. Company (fictional): HarborTech Services (HTS) –…

GLM 5.3 Prime510 words
HarborTech Services – LBO Underwriting Summary Entry Economics EV = 12.0x × $120m = $1,440m; fees = 2% × 1,440 = $28.8m; total uses = $1,468.8m Debt: Term Loan = 4.0x × 120 = $480m (9% cash, 1%/yr amort); Mezz = 1.5x × 120 = $180m (12% cash + 2% PIK) Sponsor equity = 1,468.8 − 660 = $808.8m (~55% of cap) Annual Model…
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GPT-5.6 Luna554 words
Sources, uses and operating / debt schedule Entry capitalization Entry enterprise value: (12.0 \times \$120.0 = \$1,440.0m) Transaction fees: (2.0\% \times \$1,440.0 = \$28.8m) Term Loan: (4.0 \times \$120.0 = \$480.0m) Mezzanine: (1.5 \times \$120.0 = \$180.0m) Equity contribution…
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Our Verdict
GLM 5.3 Prime
GLM 5.3 Prime
GPT-5.6 Luna
GPT-5.6 LunaRunner-up

Not enough votes to call it. On the specs, GLM 5.3 Prime has the edge: bigger model tier, newer.

Too close to call
API pricing

Cost per 1M tokens

GLM 5.3 Prime
Input
$2.80
Output
$8.80
GPT-5.6 Luna
Input
$1.00
2.8× cheaper
Output
$6.00
1.5× cheaper

GPT-5.6 Luna is cheaper on both: 2.8× input, 1.5× output.

Where to run it

4 hosts, cheapest first

GLM 5.3 Prime1 host
HostInOutContextUptime
Alibaba Cloud$2.80 in·$8.80 out·1M·99.9% up
GPT-5.6 Luna3 hosts
HostInOutContextUptime
Azure AI Foundry$0.20 in·$1.20 out·1.1M·99.5% upOpenAI$0.20 in·$1.20 out·1.1M·99.9% upAmazon Bedrock$0.22 in·$1.32 out·1.1M·100% up

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

Research

What we learned reading every model

FAQ

Common questions

GLM 5.3 Prime is developed by Z.ai while GPT-5.6 Luna is developed by OpenAI. GLM 5.3 Prime has a 1.0M token context window vs GPT-5.6 Luna's 1.1M. 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-5.6 Luna 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-5.6 Luna costs $1/M input tokens. GPT-5.6 Luna is $1.80/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-5.6 Luna 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-5.6 Luna logo
GPT-5.6 Luna58 outputs, specs and price
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