GPT-5.6 Sol vs 
Riverflow V2 Fast
GPT-5.6 Sol has a larger context window than Riverflow V2 Fast (1.1M tokens vs 8K tokens).
Written rounds
2 promptsBuy-side IC memo on a fictional SaaS company. Valuation, then the diligence questions.
Five-year LBO on a fictional HVAC business. Returns first, then the sensitivities.
Price and specs
Not enough votes to call it. On the specs, GPT-5.6 Sol has the edge: bigger model tier, newer, bigger context window, major provider backing.
| Spec | GPT-5.6 Sol | Riverflow V2 Fast |
|---|---|---|
| Input price | $5/M tokens | — |
| Output price | $30/M tokens | — |
| Context window | 1.1M tokens | 8K tokens |
| Weights | Closed | — |
| Free API (OpenRouter) | No | No |
| Released | Jul 2026 | Feb 2026 |
| At 10M a month | $50.00 | not listed |
Input tokens at list price. No caching, no batch discount.
Where to run it
Riverflow V2 Fast1 host
Per million tokens. Prices and uptime via OpenRouter, checked 10 Oct 2026.
Common questions
What is the difference between GPT-5.6 Sol and Riverflow V2 Fast?
GPT-5.6 Sol is developed by OpenAI while Riverflow V2 Fast is developed by Sourceful. GPT-5.6 Sol 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.
Which is better, GPT-5.6 Sol or Riverflow V2 Fast?
It depends on your use case. GPT-5.6 Sol 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.
How can I compare GPT-5.6 Sol and Riverflow V2 Fast on Rival?
This page shows a side-by-side comparison of GPT-5.6 Sol 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.
More comparisons
Against the newest arrivals
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- GPT-5.6 Sol vs GPT-6.1 SolLanded Sep 2026
- Riverflow V2 Fast vs Claude Sonnet 5.5Landed Sep 2026
- GPT-5.6 Sol vs Solar Mini 4Landed Sep 2026
- Riverflow V2 Fast vs Qwen3.8 Max PrimeLanded Sep 2026
Same lab, same size, long tail
- GPT-5.6 Sol vs GPT-5.6 LunaVersion compare
- GPT-5.6 Sol vs GPT-6 Luna ProSame lab
- Riverflow V2 Fast vs Ox AlphaSame size
- Riverflow V2 Fast vs GPT-6.1 SolSame size
- Riverflow V2 Fast vs Gemini 3.7 FlashSame size
- Riverflow V2 Fast vs Gemini 3.8 FlashSame size
- GPT-5.6 Sol vs Gemini Pro 1.0New provider
- GPT-5.6 Sol vs Gemma 3 12BNew provider
