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  5. GLM 5.3 FlashvsGPT-5.1 Codex Max
Updated Aug 2026

GLM 5.3 FlashvsGPT-5.1 Codex Max

GLM 5.3 Flash is the newer model, released after GPT-5.1 Codex Max.

GLM 5.3 Flash and GPT-5.1 Codex Max compared across 15 shared prompts
SpecGLM 5.3 FlashGPT-5.1 Codex Max
Input price$0.15/M tokens—
Output price$0.5/M tokens—
Context window1.3M tokens—
WeightsOpenClosed
Free API (OpenRouter)NoNo
ReleasedAug 2026Dec 2025
Side by side

Same prompt, both answers

Opening lines from 3 of the 15 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 Flash518 words
HarborTech Services — 5-Year LBO Summary Entry Math EV = 12.0x × $120m = $1,440.0m; Fees (2%) = $28.8m; Total uses = $1,468.8m Debt: TL = 4.0x × 120 = $480.0m; Mezz = 1.5x × 120 = $180.0m; Total = $660.0m (5.5x) Sponsor equity = $808.8m Base Case Projection ($m) FY26 FY27 FY28 FY29 FY30 Revenue 972.0 1,039.7 1,102.1…
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GPT-5.1 Codex Max192 words
1) Projected cash flows & debt (FY2026–FY2030, $m) (“FCF after debt service” = after interest, taxes, capex, ΔNWC, mandatory amort; applied to optional TL paydown) Year Revenue EBITDA TL Cash Int. Mezz Cash Int. Cash Taxes Capex ΔNWC FCF after debt service End TL Bal. End Mezz Bal. (incl.
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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 Flash327 words
1-Month Beginner Health & Longevity Plan 🥗 Area 1: Diet — "Add Before You Subtract" Week 1: Add one vegetable or fruit to every meal. Don't cut anything yet—just add. Week 2: Swap one sugary drink per day for water or unsweetened tea.
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GPT-5.1 Codex Max386 words
Here's a simple four‑week framework to help you ease into healthier habits. It keeps the focus on three big levers you can control and builds gradually so it feels doable. Key areas: Nourishing food, regular movement, and rest/recovery.
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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 Flash205 words
Golden Hour Garlic Butter Pasta A silky, savory pasta that comes together faster than delivery! Ingredients (serves 2): 8 oz spaghetti or any pasta 4 tbsp butter 4 cloves garlic, minced (or 1 tsp garlic powder) ½ cup grated Parmesan cheese ½ cup pasta water (reserved) 1 tsp red pepper flakes Salt Prep time: 5 minutes…
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GPT-5.1 Codex Max175 words
Sunset Chickpea & Tomato Skillet A cozy, savory one-pan dish that comes together with staples you likely have on hand. Ingredients (7): 1 can (15 oz) chickpeas, drained and rinsed 1 can (14–15 oz) crushed tomatoes 1 medium onion, finely chopped 2 cloves garlic, minced (or 1 tsp garlic powder) 2 tbsp olive oil 1 tsp…
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Our Verdict
GLM 5.3 Flash
GLM 5.3 Flash
GPT-5.1 Codex Max
GPT-5.1 Codex Max

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 Flash
Input
$0.15
Output
$0.50
GPT-5.1 Codex Max
Input
—
Output
—
Where to run it

31 hosts, cheapest first

GLM 5.3 Flash30 hosts
HostInOutContextUptime
DDeepInfrafp4$0.07 in·$0.25 out·1M·99.1% upGGMI Cloudfp8$0.07 in·$0.25 out·1M·99.1% upMMorph$0.08 in·$0.28 out·1M·99.9% upIInferenceNetfp4$0.09 in·$0.28 out·1M·97% upWWafer$0.10 in·$0.35 out·1M·99.8% upRRelace$0.11 in·$0.36 out·1M·99.6% up
24 more hostsFewer hosts
PPhalafp8$0.13 in·$0.42 out·1M·99.4% upNNovitafp8$0.13 in·$0.44 out·1M·99.4% upSStreamLakefp8$0.14 in·$0.47 out·1M·99.1% upSSail Researchfp8$0.14 in·$0.47 out·1M·98.7% upAAtlasCloudfp8$0.15 in·$0.50 out·1M·99.6% upCloudflare Workers AI$0.15 in·$0.50 out·1.3M·99.8% upCCoreWeavenvfp4$0.15 in·$0.50 out·1M·99.5% upDDigitalOcean$0.15 in·$0.50 out·1M·94.2% upFFireworks$0.15 in·$0.50 out·1M·99% upFFriendli$0.15 in·$0.50 out·1M·99.4% upIInceptronfp8$0.15 in·$0.50 out·1M·98.1% upIio.netfp8$0.15 in·$0.50 out·262k·99.2% upNNear AIfp8$0.15 in·$0.50 out·1M·98.8% upPParasailfp8$0.15 in·$0.50 out·1M·98.9% upRRekafp8$0.15 in·$0.50 out·262k·99.1% upSSiliconFlowfp8$0.15 in·$0.50 out·1M·99.7% upTTogether$0.15 in·$0.50 out·1M·99.5% upVVenice$0.15 in·$0.50 out·1M·98.7% upZ.aifp8$0.15 in·$0.50 out·1M·97% upNNextBitfp8$0.18 in·$0.60 out·1M·98.3% upModalfp8$0.45 in·$1.50 out·1M·99.5% upOOpenInferencefp4degraded$0.10 in·$0.50 out·1M·98.4% upBBasetenfp8degraded$0.15 in·$0.50 out·1M·99% upCCrusoefp4degraded$0.15 in·$0.50 out·1M·93.1% up
GPT-5.1 Codex Max1 host
HostInOutContextUptime
Azure AI Foundry$1.25 in·$10.00 out·400k·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 22 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

GLM 5.3 Flash is developed by Zhipu AI while GPT-5.1 Codex Max is developed by OpenAI. You can compare their actual outputs across 15 challenges on Rival to see how they differ in practice.

It depends on your use case. GLM 5.3 Flash and GPT-5.1 Codex Max each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 15 challenges so you can judge which fits your needs best.

This page shows a side-by-side comparison of GLM 5.3 Flash and GPT-5.1 Codex Max 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.

Keep exploring

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GLM 5.3 Flash logoDeepSeek V4 Flash Vision Exp logo
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GPT-5.1 Codex Max vs Muse Glimmer 30BLanded Sep 2026
GLM 5.3 Flash logoGLM 5.3 logo
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Same lab, same size, long tail

GLM 5.3 Flash logoGLM 5.3 FlashX logo
GLM 5.3 Flash vs GLM 5.3 FlashXSame lab
GLM 5.3 Flash logoGLM 5.2 logo
GLM 5.3 Flash vs GLM 5.2Same lab
GPT-5.1 Codex Max logoGPT-6 Astra Pro logo
GPT-5.1 Codex Max vs GPT-6 Astra ProSame lab
GPT-5.1 Codex Max logoGPT-6 Astra logo
GPT-5.1 Codex Max vs GPT-6 AstraSame lab
GLM 5.3 Flash logoGPT-5.6 Sol logo
GLM 5.3 Flash vs GPT-5.6 SolCross-provider
GLM 5.3 Flash logoGPT-5.6 Terra logo
GLM 5.3 Flash vs GPT-5.6 TerraSame size
GLM 5.3 Flash logoGPT-6 Astra logo
GLM 5.3 Flash vs GPT-6 AstraCross-provider
GLM 5.3 Flash logoGPT OSS 120B logo
GLM 5.3 Flash vs GPT OSS 120BCross-provider

Model pages

GLM 5.3 Flash logo
GLM 5.3 Flash15 outputs, specs and price
GPT-5.1 Codex Max logo
GPT-5.1 Codex Max53 outputs, specs and price
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