Grok vs StepFun Step 3.5 Flash
Which one should you pick? Here's the full breakdown.
Grok
xAI's irreverent chatbot with a direct line to X/Twitter -- real-time data meets unfiltered personality
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
| Category | Grok | StepFun Step 3.5 Flash |
|---|---|---|
| Ease of Use | 7.0 | 6.0 |
| Output Quality | 7.5 | 8.0 |
| Value | 7.5 | 9.0 |
| Features | 8.0 | 8.0 |
| Overall | 7.5 | 7.8 |
Pricing Comparison
| Feature | Grok | StepFun Step 3.5 Flash |
|---|---|---|
| Free Tier | Yes | Yes |
| Starting Price | $0 | $0 |
Benchmark Head-to-Head
Grok 4.20 benchmarks — StepFun Step 3.5 Flash has no published benchmarks
| Benchmark | Description | Score |
|---|---|---|
| MMLU | Knowledge across 57 subjects | 88.5% |
| GPQA Diamond | Graduate-level science questions | 85% |
| HumanEval | Python code generation | 90% |
| Humanity's Last Exam | Frontier difficulty questions | 50.7% |
Which Should You Pick?
Pick Grok if...
- ✓Easier to use (7 vs 6)
People who live on X/Twitter and want an AI that can tap into that data in real-time. Also good for users who find mainstream chatbots too sanitized and want something with more personality.
Visit GrokPick StepFun Step 3.5 Flash if...
- ✓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 FlashOur Verdict
Grok and StepFun Step 3.5 Flash are extremely close overall. Your choice comes down to specific needs -- Grok is better for people who live on x/twitter and want an ai that can tap into that data in real-time, while StepFun Step 3.5 Flash works best 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.