o3 Mini vs Step 3.5 Flash
How do these models stack up? Below is an expert side-by-side comparison of specifications, context window capacity, live pricing per million tokens, and standardized benchmark scores for o3 Mini and Step 3.5 Flash.
o3 Mini
OpenAI o3-mini is a cost-efficient language model optimized for STEM reasoning tasks, particularly excelling in science, mathematics, and coding. This model supports the `reasoning_effort` parameter, which can be set to...
Step 3.5 Flash
Step 3.5 Flash is StepFun's most capable open-source foundation model. Built on a sparse Mixture of Experts (MoE) architecture, it selectively activates only 11B of its 196B parameters per token....
Technical Specifications
| Specification | o3 Mini | Step 3.5 Flash |
|---|---|---|
| Provider | OpenAI | StepFun |
| Context Window | 200,000 tokens | 262,144 tokens |
| Agent Suitability | 91/100 | N/A |
| Time to First Token (TTFT) | 800 ms | N/A |
| Deployment Model | managed api | managed api |
| Production Stability | stable | stable |
| API Available | Yes | Yes |
| Released Date | 2025-01-31 | 2026-01-29 |
API Pricing Comparison
Input Price per Million Tokens
o3 Mini
$1.10
Step 3.5 Flash
$0.10
Output Price per Million Tokens
o3 Mini
$4.40
Step 3.5 Flash
$0.30
Want to test both models live?
Run side-by-side prompt prompts in our dynamic Sandbox. Check execution speeds, latency metrics, and compute actual costs in real-time.
Benchmark Performance Metrics
Scores show the raw performance percentages verified across key evaluation suites. Higher bars indicate superior accuracy and capability in that domain.
o3 Mini Quirks & Gotchas
- ▸Best cost/performance ratio for reasoning tasks in the OpenAI lineup
- ▸Still slower than GPT-5 for simple tool calls — route accordingly
Step 3.5 Flash Quirks & Gotchas
No developer gotchas reported.