StepFun: Step 3.5 Flash wins on more metrics (6 of 9), but the right pick depends on what you optimize for — see the breakdown below.
| Metric | OpenAI: o3 | StepFun: Step 3.5 Flash |
|---|---|---|
| Intelligence Index | 38.4✓ | 37.8 |
| Coding Index | 38.4✓ | 31.6 |
| GPQA Diamond | 83% | 83%✓ |
| Design Arena Elo | 1200✓ | — |
| Speed (tokens/sec) | 40 | 45✓ |
| Latency | 5.4s | 449ms✓ |
| Input price /M | $2.00 | $0.090✓ |
| Output price /M | $8.00 | $0.300✓ |
| Context window | 200K | 262K✓ |
| Capabilities | ReasoningToolsJSONVision | ReasoningToolsJSON |