Riverflow V2 Fast vs 
Solar Mini 4
Solar Mini 4 has a larger context window than Riverflow V2 Fast (524K 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
| Spec | Riverflow V2 Fast | Solar Mini 4 |
|---|---|---|
| Input price | — | $0.05/M tokens |
| Output price | — | $0.2/M tokens |
| Context window | 8K tokens | 524K tokens |
| Free API (OpenRouter) | No | No |
| Released | Feb 2026 | Sep 2026 |
| At 10M a month | not listed | $0.50 |
Input tokens at list price. No caching, no batch discount.
Where to run it
Riverflow V2 Fast1 host
Solar Mini 41 host
Per million tokens. Prices and uptime via OpenRouter, checked 29 Sep 2026.
Common questions
What is the difference between Riverflow V2 Fast and Solar Mini 4?
Riverflow V2 Fast is developed by Sourceful while Solar Mini 4 is developed by Upstage. Riverflow V2 Fast has a 8K token context window vs Solar Mini 4's 524K. You can compare their actual outputs across 2 challenges on Rival to see how they differ in practice.
Which is better, Riverflow V2 Fast or Solar Mini 4?
It depends on your use case. Riverflow V2 Fast and Solar Mini 4 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 Riverflow V2 Fast and Solar Mini 4 on Rival?
This page shows a side-by-side comparison of Riverflow V2 Fast and Solar Mini 4 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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- Riverflow V2 Fast vs GLM 5.3 PrimeLanded Sep 2026
- Solar Mini 4 vs Qwen3.8 Omni FlashLanded Sep 2026
- Riverflow V2 Fast vs Command A+Landed Sep 2026
- Solar Mini 4 vs Claude Opus 5.5Landed Sep 2026
- Riverflow V2 Fast vs GPT-6 Luna ProLanded Sep 2026
- Solar Mini 4 vs GPT-6 Sol ProLanded Sep 2026
Same lab, same size, long tail
- Riverflow V2 Fast vs Ox AlphaSame size
- Riverflow V2 Fast vs MiniMax M3Same size
- Solar Mini 4 vs Solar Pro 4Same lab
- Solar Mini 4 vs Solar Pro 3Same lab
- Riverflow V2 Fast vs Claude Sonnet 3.6 (2022-10-22)Same size
- Riverflow V2 Fast vs Claude 3.7 SonnetSame size
- Riverflow V2 Fast vs Claude 3.7 Thinking SonnetSame size
- Solar Mini 4 vs Claude Sonnet 4.5New provider
