StepFun Step 3.5 Flash vs Synthesia
Which one should you pick? Here's the full breakdown.
StepFun Step 3.5 Flash
StepFun's (China) agent-focused open-weight model -- Step 3.5 Flash launched 2026-02-01. 196B sparse MoE, ~11B active. Benchmarks slightly ahead of DeepSeek V3.2 at over 3x smaller total size. Step 3 (321B / 38B active, Apache 2.0) and Step3-VL-10B multimodal also in the family
Synthesia
Create talking-head videos with AI avatars -- no camera, no actors, no studio needed
| Category | StepFun Step 3.5 Flash | Synthesia |
|---|---|---|
| Ease of Use | 6.0 | 9.0 |
| Output Quality | 8.0 | 7.0 |
| Value | 9.0 | 6.0 |
| Features | 8.0 | 8.0 |
| Overall | 7.8 | 7.5 |
Pricing Comparison
| Feature | StepFun Step 3.5 Flash | Synthesia |
|---|---|---|
| Free Tier | Yes | Yes |
| Starting Price | $0 | $0 |
Which Should You Pick?
Pick StepFun Step 3.5 Flash if...
- ✓Higher output quality (8 vs 7)
- ✓Better value for money (9/10)
Teams building agent systems on Chinese open-weight foundations who want something other than DeepSeek or Qwen, especially if agentic tool-use is the primary workload. Also good for Chinese-market products where StepFun's domestic tuning advantages matter. And for anyone looking to add diversity to their open-weight evaluation matrix beyond the top-3 Chinese labs.
Visit StepFun Step 3.5 FlashPick Synthesia if...
- ✓Easier to use (9 vs 6)
Corporate teams producing training, onboarding, and internal comms videos at scale across multiple languages.
Visit SynthesiaOur Verdict
StepFun Step 3.5 Flash and Synthesia are extremely close overall. Your choice comes down to specific needs -- StepFun Step 3.5 Flash is better for teams building agent systems on chinese open-weight foundations who want something other than deepseek or qwen, especially if agentic tool-use is the primary workload, while Synthesia works best for corporate teams producing training, onboarding, and internal comms videos at scale across multiple languages.