Step 3.5 Flash 2603
Summary
Step 3.5 Flash 2603 is an open-weight language model from StepFun, released on 2 Apr 2026. It accepts text and generates text, with a 256K-token context window and up to 131K output tokens per response.
StepFun flash model for efficient multimodal reasoning, coding, and tool use
Last verified 4 Oct 2026. Every figure on this page links to its source.
Specifications
| Developer | StepFun |
|---|---|
| Release date | 2 Apr 2026 [models.dev] |
| Status | Generally available [models.dev] |
| Weights | Open weights [models.dev] |
| Context window | 256K (256,000 tokens) [models.dev] |
| Max output | 131K tokens [models.dev] |
| Knowledge cutoff | Jan 2025 [models.dev] |
| Input | Text [models.dev] |
| Output | Text [models.dev] |
| Reasoning mode | Yes [models.dev] |
| Tool calling | Yes [models.dev] |
| Structured output | Yes [models.dev] |
Step 3.5 Flash 2603 API pricing by provider
USD per million tokens. Sorted by input price.
We do not currently track a paid API listing for this model.
Frequently asked questions
What is the context window of Step 3.5 Flash 2603?
Step 3.5 Flash 2603 has a context window of 256,000 tokens (256K) and can generate up to 131,072 tokens in a single response, according to models.dev.
Is Step 3.5 Flash 2603 open source?
Step 3.5 Flash 2603 is an open-weight model. Check the license terms before commercial use.
When was Step 3.5 Flash 2603 released?
StepFun released Step 3.5 Flash 2603 on 2 Apr 2026, according to models.dev.
Change history
No changes detected since we started tracking this model. We re-check every source daily.