Kimi K3: 2.8T Open-Weight Multimodal Model

Kimi K3, developed by Moonshot AI, represents a landmark achievement in open-source artificial intelligence. As a 2.8-trillion-parameter native multimodal Mixture-of-Experts (MoE) model, Kimi K3 is engineered to handle demanding computational tasks, from complex software engineering and long-horizon agentic workflows to deep scientific research.

By combining a one-million-token context window with its architectural innovations, Kimi K3 offers frontier-level performance that rivals the world’s leading proprietary models. This overview covers the model’s capabilities, performance benchmarks, and how to integrate it via the DeepInfra platform.

Architectural Innovation and Efficiency

Kimi K3 introduces several breakthroughs designed to maximize reasoning power while maintaining operational efficiency. Unlike traditional dense models, Kimi K3 utilizes a Stable LatentMoE framework. While the model contains 896 experts, it activates only 16 per token, totaling 104 billion active parameters. This design results in a 2.5x improvement in scaling efficiency compared to its predecessor, Kimi K2.

Key Technologies

• Kimi Delta Attention (KDA) & Attention Residuals (AttnRes): These mechanisms optimize long-context processing, enabling the model to maintain high performance across its entire 1M-token window.
• Native Multimodality: Kimi K3 is built from the ground up to process text, images, and video within a single unified framework, rather than relying on external plugins.
• Quantization-Aware Training (QAT): The model features native MXFP4 weights and MXFP8 activations, ensuring broad hardware compatibility and efficient inference without sacrificing accuracy.

Performance Benchmarks

Kimi K3 consistently delivers top-tier results across reasoning, coding, and vision benchmarks, often setting the standard for open-weight models and matching proprietary systems like GPT-5.6 Sol and Claude Fable 5.

Comparative Performance Overview

Specialized Capabilities

• Engineering & Coding: Kimi K3 is optimized for long-horizon tasks, sustaining engineering sessions across large repositories and orchestrating terminal tools for GPU kernel optimization and compiler development, with minimal human oversight.
• Agentic Knowledge Work: The model advances end-to-end knowledge work, producing deep research with interactive visualizations, widgets, and dashboards. It scored 94.5 on MCPMark-Verified, indicating strong reliability in tool-calling environments.
• Document & Video Intelligence: With a score of 91.1 on OmniDocBench, Kimi K3 leads in document layout analysis, and its native multimodal architecture also supports motion design and video editing tasks.

Getting Started with the Kimi K3 API

DeepInfra provides an OpenAI-compatible interface for Kimi K3, making it easy to integrate into existing workflows. The model is listed on the DeepInfra model catalog alongside DeepInfra’s broader lineup of open-weight models.

Authentication

To interact with the API, you must use a DeepInfra API key. Retrieve your key from your DeepInfra Dashboard and pass it as a Bearer token in your HTTP headers:

Authorization: Bearer <YOUR_DEEPINFRA_API_KEY>

API Endpoint Basics

• Base URL: https://api.deepinfra.com/v1/openai
• Chat Completions Path: /chat/completions
• Method: POST

Using cURL

curl https://api.deepinfra.com/v1/openai/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $DEEPINFRA_API_KEY" \
  -d '{
    "model": "moonshotai/Kimi-K3",
    "messages": [
      {
        "role": "user",
        "content": "Explain the benefits of Kimi Delta Attention for long-context reasoning."
      }
    ],
    "temperature": 0.2
  }'
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Using Python

import os
import requests

api_key = os.getenv("DEEPINFRA_API_KEY")
url = "https://api.deepinfra.com/v1/openai/chat/completions"

headers = {
    "Authorization": f"Bearer {api_key}",
    "Content-Type": "application/json"
}

payload = {
    "model": "moonshotai/Kimi-K3",
    "messages": [{"role": "user", "content": "Write a Python function to optimize a GPU kernel."}],
    "temperature": 0.2
}

response = requests.post(url, headers=headers, json=payload)
print(response.json())
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Configuration and Parameters

When sending requests to the /chat/completions endpoint, you can fine-tune the model’s behavior using the following parameters. The full parameter reference is available in the Kimi K3 API documentation.

Pricing and Token Usage

DeepInfra offers a transparent, usage-based pricing model for Kimi K3. The model supports cached input pricing, which significantly reduces costs for repeated long-context tasks by billing cached tokens at a fraction of the standard input rate.

For the most up-to-date information regarding volume discounts or tier-based pricing, refer to the official DeepInfra pricing page.

Final Thoughts

Kimi K3 stands as a powerful, cost-effective alternative to proprietary frontier models. Its combination of a 2.8T-parameter architecture, 1M-token context window, and native multimodality makes it a strong choice for developers building the next generation of AI agents and complex engineering tools. Here are the key takeaways:

• Frontier Performance: Matches or approaches top-tier proprietary models in coding and reasoning.
• Architectural Efficiency: 2.5x scaling improvement via KDA and MoE.
• Developer Friendly: OpenAI-compatible API with support for JSON mode and function calling.

To begin using Kimi K3 for your projects, visit the DeepInfra Dashboard to retrieve your API key or deploy a private endpoint for dedicated capacity.