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  5. GPT-6 Luna ProvsRiverflow V2 Fast
Updated Sep 2026

GPT-6 Luna ProvsRiverflow V2 Fast

GPT-6 Luna Pro has a larger context window than Riverflow V2 Fast (1.1M tokens vs 8K tokens).

GPT-6 Luna Pro and Riverflow V2 Fast compared across 2 shared prompts
SpecGPT-6 Luna ProRiverflow V2 Fast
Input price$0.1/M tokens—
Output price$0.5/M tokens—
Context window1.1M tokens8K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedSep 2026Feb 2026
Our Verdict
GPT-6 Luna Pro
GPT-6 Luna Pro
Riverflow V2 Fast
Riverflow V2 FastRunner-up

Not enough votes to call it. On the specs, GPT-6 Luna Pro has the edge: newer, bigger context window, major provider backing.

Too close to call
API pricing

Cost per 1M tokens

GPT-6 Luna Pro
Input
$0.10
Output
$0.50
Riverflow V2 Fast
Input
—
Output
—
Where to run it

3 hosts

GPT-6 Luna Pro2 hosts
HostInOutContextUptime
Azure AI Foundry$0.10 in·$0.50 out·1.1M·98.6% upOpenAI$0.10 in·$0.50 out·1.1M·99.9% up
Riverflow V2 Fast1 host
HostInOutContextUptime
SSourceful$0 in·$0 out·8k·100% up

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

Research

What we learned reading every model

FAQ

Common questions

GPT-6 Luna Pro is developed by OpenAI while Riverflow V2 Fast is developed by Sourceful. GPT-6 Luna Pro has a 1.1M token context window vs Riverflow V2 Fast's 8K. You can compare their actual outputs across 2 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-6 Luna Pro and Riverflow V2 Fast each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 2 challenges so you can judge which fits your needs best.

This page shows a side-by-side comparison of GPT-6 Luna Pro and Riverflow V2 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.

Keep exploring

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Same lab, same size, long tail

GPT-6 Luna Pro logoGPT-6 Sol Pro logo
GPT-6 Luna Pro vs GPT-6 Sol ProSame lab
GPT-6 Luna Pro logoGPT-6 Luna logo
GPT-6 Luna Pro vs GPT-6 LunaSame lab
Riverflow V2 Fast logoOx Alpha logo
Riverflow V2 Fast vs Ox AlphaSame size
Riverflow V2 Fast logoMiniMax M3 logo
Riverflow V2 Fast vs MiniMax M3Same size
Riverflow V2 Fast logoGPT-5.4 Mini logo
Riverflow V2 Fast vs GPT-5.4 MiniCross-provider
Riverflow V2 Fast logoGPT-5.4 Nano logo
Riverflow V2 Fast vs GPT-5.4 NanoCross-provider
Riverflow V2 Fast logoGPT-5.4 Pro logo
Riverflow V2 Fast vs GPT-5.4 ProCross-provider
Riverflow V2 Fast logoGPT-5.5 logo
Riverflow V2 Fast vs GPT-5.5Cross-provider

Model pages

GPT-6 Luna Pro logo
GPT-6 Luna Pro20 outputs, specs and price
Riverflow V2 Fast logo
Riverflow V2 Fast2 outputs, specs and price
Rival
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Explore all of Rival

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