Riverflow V2.5 Fast vs 
Seedream 4
Riverflow V2.5 Fast is the newer model, released after Seedream 4.
Hyperrealistic Portrait
One prompt, one photorealistic portrait. Skin, eyes, light.
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Which answer wins?
Price and specs
| Spec | Riverflow V2.5 Fast | Seedream 4 |
|---|---|---|
| Input price | Free | — |
| Output price | Free | — |
| Context window | 8K tokens | — |
| Free API (OpenRouter) | No | — |
| Released | Jun 2026 | Nov 2025 |
| At 10M a month | $0 | not listed |
Input tokens at list price. No caching, no batch discount.
Where to run it
Riverflow V2.5 Fast1 host
Seedream 4
No hosts listed on OpenRouter.
Per million tokens. Prices and uptime via OpenRouter, checked 10 Oct 2026.
Common questions
What is the difference between Riverflow V2.5 Fast and Seedream 4?
Riverflow V2.5 Fast is developed by Sourceful while Seedream 4 is developed by ByteDance. You can compare their actual outputs across 17 challenges on Rival to see how they differ in practice.
Which is better, Riverflow V2.5 Fast or Seedream 4?
It depends on your use case. Riverflow V2.5 Fast and Seedream 4 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 17 challenges so you can judge which fits your needs best.
How can I compare Riverflow V2.5 Fast and Seedream 4 on Rival?
This page shows a side-by-side comparison of Riverflow V2.5 Fast and Seedream 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
- Riverflow V2.5 Fast vs Hy Image 3.5 PreviewLanded Oct 2026
- Seedream 4 vs FLUX.3 ImageLanded Oct 2026
- Riverflow V2.5 Fast vs Nano Banana 2.1Landed Oct 2026
- Seedream 4 vs Recraft V4.1 FlashLanded Sep 2026
- Riverflow V2.5 Fast vs GPT Image 2.5 SunburstLanded Sep 2026
- Seedream 4 vs GPT Image 2.5 FlareLanded Sep 2026
- Riverflow V2.5 Fast vs Nano Banana 2 LiteLanded Jun 2026
- Seedream 4 vs Riverflow V2.5 ProLanded Jun 2026
Same lab, same size, long tail
- Riverflow V2.5 Fast vs Riverflow V2.5 ProSame lab
- Riverflow V2.5 Fast vs FLUX.3 ImageSame size
- Seedream 4 vs Hy Image 3.5 PreviewSame size
- Seedream 4 vs Nano Banana 2.1Same size
- Riverflow V2.5 Fast vs FLUX 2 ProSame size
- Riverflow V2.5 Fast vs FLUX Kontext MaxSame size
- Riverflow V2.5 Fast vs FLUX Kontext ProSame size
- Riverflow V2.5 Fast vs FLUX ProSame size