What is the context window of Fusion by OpenRouter?

Fusion by OpenRouter has a context window of 1.0M tokens. It supports up to 1.0M input tokens and can generate up to 128K output tokens.

What input and output types does Fusion support?

Fusion by OpenRouter accepts text as input and can generate text as output.

Is Fusion by OpenRouter open source?

No, Fusion by OpenRouter has closed weights. The model is only available through the OpenRouter API.

Back to Models

Fusion API

OpenRouter

About

Process massive datasets with Fusion, featuring an expansive 1.0M context window for long-document analysis. This model delivers available completely free of charge. Access Fusion via the OpenRouter API with up to 128K output tokens.

Capabilities

Input Modalities

text

Output Modalities

text

Reasoning

Structured Output

Tool Use

WeightsClosed

Temperature

Fixed

Attachment

Not Supported

Limits

Context Window

1.0M

Tokens

Input Limit

1.0M

Tokens

Max Output

128K

Tokens

Pricing

Standard (per 1M tokens)

Input

Free

Output

Free

Frequently Asked Questions

Fusion by OpenRouter costs Free per 1M input tokens and Free per 1M output tokens.

Model Details

openrouter/fusion

Provider

OpenRouter

Family

Release Date

Jun 13, 2026

Knowledge Cutoff

N/A

API Integration

NPM Package

@openrouter/ai-sdk-provider

Environment Variables

OPENROUTER_API_KEY

API Base URL

https://openrouter.ai/api/v1

Documentation