StepFun / stepfun/step-3.5-flash-2603
Step 3.5 Flash 2603 - access through LLMTR
Step 3.5 Flash 2603 is the controllable-reasoning variant in the Step 3.5 Flash family. It supports text Chat Completions, tool calling, and JSON mode; reasoning_effort low and high can be selected with request parameters.
Technical specifications
| Canonical ID | stepfun/step-3.5-flash-2603 |
|---|---|
| Provider | StepFun |
| Context window | 256,000 tokens |
| Operations | CHAT_COMPLETIONS |
| Modalities | text |
Pricing
A 6% platform margin applies to credit top-ups; model usage prices are not separately marked up.
| Operation | Metric | Unit | Price |
|---|---|---|---|
| CHAT_COMPLETIONS | CACHE_READ | PER_1M_TOKENS | Not available |
| CHAT_COMPLETIONS | INPUT_TEXT | PER_1M_TOKENS | Not available |
| CHAT_COMPLETIONS | OUTPUT_TEXT | PER_1M_TOKENS | Not available |
Example usage
With existing OpenAI SDK flows, change only the base URL and model identifier.
curl https://llmtr.com/v1/chat/completions \
-H "Authorization: Bearer llmtr-your_key" \
-H "Content-Type: application/json" \
-d '{"model":"stepfun/step-3.5-flash-2603","messages":[{"role":"user","content":"Hello"}]}'Related models
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- Step 3.5 Flash stepfun/step-3.5-flash
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- GPT-5.5 openai/gpt-5.5
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