StepFun · Released Apr 2, 2026Step 3.5 Flash 2603
StepFun flash model for efficient multimodal reasoning, coding, and tool use.
- Capability
- —No ECI score yet
- Input
- $0.10per 1M tokens
- Output
- $0.30per 1M tokens
- Context
- 256K256K max output
What it costs
- Input
- $0.10per million tokens
- Output
- $0.30per million tokens
- Cached input
- $0.02per million tokens
- Blended (3:1)
- $0.15cheaper than 83% of priced models
Typical monthly bills
| Monthly usage | Estimated cost |
|---|---|
| Side project2M input + 0.5M output tokens | $0.35 |
| Team assistant25M input + 5M output tokens | $4.00 |
| Production app250M input + 50M output tokens | $40.00 |
Official StepFun (Global) API price, as listed on models.dev.
Independent benchmarks
Epoch AI has not published a Capabilities Index score for Step 3.5 Flash 2603 yet.
The details
- Lab
- StepFun
- Released
- Apr 2, 2026
- Knowledge cutoff
- Jan 2025
- Context window
- 256,000 tokens
- Max output
- 256,000 tokens
- Inputs
- Text
- Output
- Text
- Reasoning
- Adjustable effort low · high
- Tool calling
- Yes
- Structured output
- No
- Weights
- Open weights
- API model ID
step-3.5-flash-2603on StepFun (Global)- Availability
- 3 API providerslisted on models.dev
What StepFun claims
Published by the lab at launch. Settings vary, so compare these only with care.
More from StepFun
About Step 3.5 Flash 2603
How much does Step 3.5 Flash 2603 cost?
Step 3.5 Flash 2603 costs $0.10 input / $0.30 output per million tokens (official StepFun (Global) API price). Cached input is $0.02 per million tokens. At a 3:1 input-to-output mix that is $0.15 per million tokens, cheaper than 83% of the 360 priced models we track.
What is the context window of Step 3.5 Flash 2603?
Step 3.5 Flash 2603 accepts up to 256,000 tokens per request and can write up to 256,000 tokens in one response.
How good is Step 3.5 Flash 2603?
Epoch AI has not published a Capabilities Index score for Step 3.5 Flash 2603 yet.
Is Step 3.5 Flash 2603 open source?
Yes. StepFun publishes the weights, so it can be downloaded and self-hosted.
What inputs does Step 3.5 Flash 2603 support?
Step 3.5 Flash 2603 accepts text and replies in text. It is a reasoning model with low and high effort settings, supports tool calling.
When was Step 3.5 Flash 2603 released?
StepFun released Step 3.5 Flash 2603 on Apr 2, 2026. Its training data runs to Jan 2025.
What are the best alternatives to Step 3.5 Flash 2603?
The closest current models from other labs on capability, price and release date are MiMo-V2.5 (Xiaomi, $0.14 / $0.28), Gemma 4 E4B IT (Google, $0.11 / $0.15), GLM-4.7-FlashX (Z.ai (Zhipu), $0.07 / $0.40) and Seed Character (ByteDance Seed, $0.119 / $0.297).