# StepFun: 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....

[Compare this model](/content/models/compare?model1=stepfun-step-3-5-flash/index.html)

$0.10/1M input tokens†

Context Window

262,144 tokens

Max Output

65,536 tokens

Input Modalities

text

## Try StepFun: Step 3.5 Flash in Kilo Code

Experience this model with the most popular open source coding agent. Free to start, pay only for AI usage. Use in popular IDEs like VS Code, JetBrains, command line, or cloud agents.

2.3M+

Downloads

500+

models supported

Free

to Start

Access 500+ models including StepFun: Step 3.5 Flash and many more in Kilo Code

## Benchmarking StepFun: Step 3.5 Flash

## Real-World Usage

Real-world usage statistics from the Kilo Code community

### Weekly Token Usage

Apr 13Apr 14Apr 15Apr 16Apr 17Apr 18Apr 19020.0M40.0M60.0M80.0M

### Mode Rankings (Last Week)

Where this model ranks for each built-in mode

#### Architect

Plan and design before implementation

No data

#### Code

Write, modify, and refactor code

No data

#### Ask

Get answers and explanations

No data

#### Debug

Diagnose and fix software issues

#17

#### Orchestrator

Coordinate tasks across multiple modes

No data

## Pricing

Cost per 1 million tokens

Input Tokens

$0.10

per 1M tokens

Output Tokens

$0.30

per 1M tokens

### Example Cost

Analyzing a 10,000 line codebase (≈40k input tokens, 10k output tokens) costs approximately $0.0070

## Coding Capabilities

Features and parameters relevant to coding tasks

### Coding Features

- Function Calling
- Can call external functions/APIs
- Tool Choice
- Control over function selection
- Structured Outputs
- JSON schema validation
- Reasoning Tokens
- Extended thinking for complex problems

## Technical Details

Architecture and implementation specifications

Model ID

stepfun/step-3.5-flash

Created

January 29, 2026

Tokenizer

Other

Input Modalities

text

Context Window

262,144 tokens

Max Completion Tokens

65,536 tokens

Input Price

$0.10 per 1M tokens

Output Price

$0.30 per 1M tokens

Content Moderation

Disabled

## Ready to try StepFun: Step 3.5 Flash?

Install Kilo Code and start using StepFun: Step 3.5 Flash for your coding projects today.