StepFun Step 3.5 Flash vs Bolt.new
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
Bolt.new
AI full-stack web app builder by StackBlitz -- describe what you want and it writes the code in the browser
| Category | StepFun Step 3.5 Flash | Bolt.new |
|---|---|---|
| Ease of Use | 6.0 | 8.0 |
| Output Quality | 8.0 | 6.0 |
| Value | 9.0 | 5.0 |
| Features | 8.0 | 7.0 |
| Overall | 7.8 | 6.5 |
Pricing Comparison
| Feature | StepFun Step 3.5 Flash | Bolt.new |
|---|---|---|
| Free Tier | Yes | Yes |
| Starting Price | $0 | $0 |
Which Should You Pick?
Pick StepFun Step 3.5 Flash if...
- ✓Higher output quality (8 vs 6)
- ✓Better value for money (9/10)
- ✓More features (8 vs 7)
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 Bolt.new if...
- ✓Easier to use (8 vs 6)
Non-developers who want to quickly prototype a web app idea and don't need production quality. Also useful for developers who want to scaffold boilerplate fast and then take over manually.
Visit Bolt.newOur Verdict
StepFun Step 3.5 Flash is the clear winner here with 7.8/10 vs 6.5/10. Bolt.new isn't bad, but StepFun Step 3.5 Flash outperforms it across the board. Pick Bolt.new only if non-developers who want to quickly prototype a web app idea and don't need production quality.