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  5. GLM 5.3 PrimevsGrok 4.1 Fast
Updated Sep 2026

GLM 5.3 PrimevsGrok 4.1 Fast

GLM 5.3 Prime is the newer model, released after Grok 4.1 Fast.

GLM 5.3 Prime and Grok 4.1 Fast compared across 16 shared prompts
SpecGLM 5.3 PrimeGrok 4.1 Fast
Input price$2.8/M tokens—
Output price$8.8/M tokens—
Context window1.0M tokens—
Free API (OpenRouter)NoNo
ReleasedSep 2026Nov 2025
Side by side

Same prompt, both answers

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

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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Grok 4.1 Fast385 words
Simplified LBO Model (FY2026–FY2030, $m) Year Revenue EBITDA TL Cash Int. Mezz Cash Int. Cash Taxes Capex ΔNWC FCF After Debt Service* End TL End Mezz End Total Debt FY26 972.0 136.1 43.2 21.6 17.8 29.2 0.4 19.1 456.1 183.6 639.7 FY27 1,040.0 156.0 41.1 22.0 23.2 31.2 0.3 33.6 417.9 187.3 605.2 FY28 1,102.4 176.4 37.6…
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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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Grok 4.1 Fast659 words
Comprehensive 3-Month Longevity Biohacking Plan Introduction and Assumptions This plan is designed for an advanced biohacker (healthy adult, age 30-50, no major medical conditions) aiming to optimize longevity markers (e.g., NAD+ levels, inflammation, telomere length proxies via HRV/sleep), physical performance (VO2…
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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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Grok 4.1 Fast555 words
1-Month Plan for Better Health and Longevity This beginner-friendly plan focuses on three foundational areas: Diet, Exercise, and Sleep. These pillars drive longevity by reducing inflammation, building resilience, and optimizing recovery. Commit to small, consistent changes—aim for 80% adherence.
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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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Grok 4.1 Fast1,106 words
Analysis of Exploitable Clauses Below, I identify all nine clauses as potentially exploitable against the Contractor, explain the risks (how they could be abused), propose specific modifications to make the contract more balanced, and provide legal reasoning grounded in general principles of U.S.
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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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Grok 4.1 Fast208 words
Pantry Raid Garlic Tomato Pasta A savory, garlicky one-pan wonder that's ready in under 20 minutes—perfect for when hunger strikes and the fridge is empty! Serves: 2 Prep time: 5 minutes Cook time: 12 minutes Total time: 17 minutes Ingredients (exactly 7 common pantry staples): 200g spaghetti or any pasta (2 handfuls)…
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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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Grok 4.1 Fast346 words
No Sticky Sessions for WebSockets (Scaling Bottleneck & Failure Mode) Issue: Round-robin load balancer doesn't guarantee client WebSocket connections stick to the same API server.
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Our Verdict
Grok 4.1 Fast
Grok 4.1 Fast
GLM 5.3 Prime
GLM 5.3 PrimeRunner-up

Not enough votes to call it. On the specs, Grok 4.1 Fast has the edge: bigger model tier, major provider backing.

Too close to call
API pricing

Cost per 1M tokens

GLM 5.3 Prime
Input
$2.80
Output
$8.80
Grok 4.1 Fast
Input
—
Output
—
Where to run it

1 host

GLM 5.3 Prime1 host
HostInOutContextUptime
Alibaba Cloud$2.80 in·$8.80 out·1M·99.9% up
Grok 4.1 Fast

No hosts listed on OpenRouter.

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 Grok 4.1 Fast is developed by xAI. 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 Grok 4.1 Fast 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.

This page shows a side-by-side comparison of GLM 5.3 Prime and Grok 4.1 Fast 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
Grok 4.1 Fast logo
Grok 4.1 Fast59 outputs, specs and price
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