FLUX.2 Klein 4B API
About
Integrate multimodal vision capabilities using FLUX.2 Klein 4B, designed to process both text and images seamlessly. This model delivers available completely free of charge, open weights architecture. Access FLUX.2 Klein 4B via the OpenRouter API with up to 41K output tokens.
Capabilities
Input Modalities
imagetext
Output Modalities
image
Reasoning
No
Structured Output
No
Tool Use
No
WeightsOpen
Temperature
Adjustable
Attachment
Not Supported
Limits
Context Window
41K
Tokens
Input Limit
41K
Tokens
Max Output
41K
Tokens
Pricing
Standard (per 1M tokens)
Input
Free
Output
Free
Frequently Asked Questions
FLUX.2 Klein 4B by OpenRouter costs Free per 1M input tokens and Free per 1M output tokens.
Model Details
ID
black-forest-labs/flux.2-klein-4b
Provider
OpenRouterFamily
flux
Release Date
Jan 14, 2026
Knowledge Cutoff
Jun 1, 2025
API Integration
NPM Package
@openrouter/ai-sdk-provider
Environment Variables
OPENROUTER_API_KEY
API Base URL
https://openrouter.ai/api/v1