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....

#88 Code Mode‡$0.10/1M input tokens†
‡Kilo Code Leaderboard†OpenRouterPinchBench
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

Get Started with Kilo

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

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

#88

Ask

Get answers and explanations

No data

Debug

Diagnose and fix software issues

No data

Orchestrator

Coordinate tasks across multiple modes

No data

Real-world metrics from the Kilo Code Leaderboard

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

Pricing details from OpenRouter

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. Choose from 500+ AI models with complete freedom.

Get Started with Kilo