Arcee Trinity-Large-Thinking vs StepFun Step 3.5 Flash
Which one should you pick? Here's the full breakdown.
Arcee Trinity-Large-Thinking
Arcee AI's US-made open-weight frontier reasoning model -- launched 2026-04-01. 398B total params, ~13B active. Sparse MoE (256 experts, 4 active = 1.56% routing). Apache 2.0, trained from scratch. #2 on PinchBench trailing only Claude 3.5 Opus. ~96% cheaper than Opus-4.6 on agentic tasks
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 | Arcee Trinity-Large-Thinking | StepFun Step 3.5 Flash |
|---|---|---|
| Ease of Use | 6.0 | 6.0 |
| Output Quality | 9.0 | 8.0 |
| Value | 9.5 | 9.0 |
| Features | 8.0 | 8.0 |
| Overall | 8.1 | 7.8 |
Pricing Comparison
| Feature | Arcee Trinity-Large-Thinking | StepFun Step 3.5 Flash |
|---|---|---|
| Free Tier | Yes | Yes |
| Starting Price | $0 | $0 |
Which Should You Pick?
Pick Arcee Trinity-Large-Thinking if...
- ✓Higher output quality (9 vs 8)
Teams that need a US-made, Apache 2.0, frontier-tier open-weight model and can either rent multi-GPU infrastructure or pay OpenRouter API pricing at ~$0.90/M output tokens. Particularly valuable for US government, defense, or regulated enterprise contexts where country-of-origin matters for procurement. Also good for agentic reasoning workloads where the ~96% cost savings vs Claude Opus actually changes what you can build.
Visit Arcee Trinity-Large-ThinkingPick StepFun Step 3.5 Flash if...
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
Arcee Trinity-Large-Thinking and StepFun Step 3.5 Flash are extremely close overall. Your choice comes down to specific needs -- Arcee Trinity-Large-Thinking is better for teams that need a us-made, apache 2, 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.