GPT-6.1 Sol vs 
Riverflow V2 Fast
GPT-6.1 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-6.1 Sol has the edge: newer, bigger context window, major provider backing.
| Spec | GPT-6.1 Sol | Riverflow V2 Fast |
|---|---|---|
| Input price | $2/M tokens | — |
| Output price | $10/M tokens | — |
| Context window | 1.1M tokens | 8K tokens |
| Weights | Closed | — |
| Free API (OpenRouter) | No | No |
| Released | Sep 2026 | Feb 2026 |
| At 10M a month | $20.00 | 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 7 Oct 2026.
Common questions
What is the difference between GPT-6.1 Sol and Riverflow V2 Fast?
GPT-6.1 Sol is developed by OpenAI while Riverflow V2 Fast is developed by Sourceful. GPT-6.1 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-6.1 Sol or Riverflow V2 Fast?
It depends on your use case. GPT-6.1 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-6.1 Sol and Riverflow V2 Fast on Rival?
This page shows a side-by-side comparison of GPT-6.1 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
- GPT-6.1 Sol vs Ling 3.1 FlashLanded Oct 2026
- Riverflow V2 Fast vs Mistral Large 4Landed Oct 2026
- GPT-6.1 Sol vs Claude Sonnet 5.5Landed Sep 2026
- Riverflow V2 Fast vs Solar Mini 4Landed Sep 2026
- GPT-6.1 Sol vs Qwen3.8 Max PrimeLanded Sep 2026
- Riverflow V2 Fast vs GLM 5.3 PrimeLanded Sep 2026
- GPT-6.1 Sol vs Qwen3.8 Omni FlashLanded Sep 2026
- Riverflow V2 Fast vs Command A+Landed Sep 2026
Same lab, same size, long tail
- GPT-6.1 Sol vs GPT-6 Astra ProVersion compare
- GPT-6.1 Sol vs GPT-6 Luna ProSame lab
- Riverflow V2 Fast vs Ox AlphaSame size
- Riverflow V2 Fast vs MiniMax M3Same size
- GPT-6.1 Sol vs Qwen3 CoderNew provider
- GPT-6.1 Sol vs Qwen3 Coder FlashNew provider
- GPT-6.1 Sol vs Qwen3 Coder NextSame size
- GPT-6.1 Sol vs Qwen3 Coder PlusSame size
