Kimi K3 Fast
Fast-inference variant of Moonshot's 2.8T-parameter Kimi K3, optimized for low-latency multimodal reasoning and agentic workflows with 1M context.
Overview
What is Kimi K3 Fast
Kimi K3 Fast is a fast-inference variant of Moonshot AI's Kimi K3 model, released on July 27, 2026. It delivers the same 2.8-trillion-parameter multimodal intelligence as the base K3 but optimized for lower latency, making it ideal for real-time agentic coding, vision tasks, and long-horizon reasoning within a 1-million-token context window.
Running it privately on Venice
On Venice, Kimi K3 Fast runs with zero retention — your prompts are never stored, profiled, or used for training. This means you get the full power of a frontier multimodal model with private, end-to-end uncensored access, ideal for sensitive coding, research, or enterprise workflows where data sovereignty matters. The model's open weights and Venice's permissionless infrastructure ensure full compliance without sacrificing performance.
Assessment
Strengths and limitations
- Massive 1-million-token context window enables processing of entire codebases, books, or long video transcripts in a single pass.
- Native multimodal vision and reasoning capabilities support image input, PDF analysis, and complex agentic workflows.
- Optimized for low-latency inference, making it suitable for real-time coding agents, interactive research, and dynamic planning.
- Open weights allow for transparency and future self-hosting or fine-tuning options, unlike closed rivals.
- Supports tool use, web search, and structured JSON output, enabling robust agent frameworks and API integrations.
- Higher output cost at $22.50 per million tokens makes sustained generation expensive compared to cheaper open models.
- No end-to-end encryption or TEE protection on Venice, limiting use in highly regulated environments despite zero retention.
- Vision output is text-only: cannot generate or edit images, only interpret them.
- Still new: lacks third-party benchmark validation and real-world stress testing across diverse domains.
Capabilities
What it supports
- Tool use / function calling
- Vision (image input)
- Reasoning
- Web search
- Code-optimized
- Structured output (JSON schema)
- Audio input
- Video input
- Multiple image inputs
- Log probabilities
Specifications
Datasheet
- Maker
- Moonshot AI
- Released
- July 27, 2026
- Architecture
- Stable LatentMoE with Kimi Delta Attention (KDA) and Attention Residuals (AttnRes)
- Parameters
- 2.8 trillion (total), 16 of 896 experts active per token
- Open weights
- Yes — Apache-style license
- Context window
- 1,000K tokens
- Max output
- 131.072K tokens
- Capabilities
- Vision, Function calling, Reasoning, Web search, Code-optimized
- Privacy on Venice
- Private — zero retention
- Available on Venice since
- Aug 2026
- License
- Other
API
Call it from your code
Venice exposes an OpenAI-compatible API. Point your base URL at Venice and pass the model id.
curl https://api.venice.ai/api/v1/chat/completions \
-H "Authorization: Bearer $VENICE_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "kimi-k3-fast-api",
"messages": [{ "role": "user", "content": "Explain quantum tunneling simply." }]
}'Pricing
What it costs on Venice
Billed per token on Venice: $4.50 per 1M input tokens and $22.50 per 1M output tokens.
New Venice accounts include a free daily allowance and 500 welcome credits — no credit card required.
Alternatives
How it compares
| Model | Max resolution | Strongest at | Open weights | Price (Venice) |
|---|---|---|---|---|
| Kimi K3 Fast | N/A | Long-context agentic coding, multimodal reasoning | Yes | $4.50 in · $22.50 out / 1M |
| Claude Opus 5 | N/A | High-stakes reasoning, enterprise safety | No | $6 in · $30 out / 1M |
| DeepSeek V4 Flash 0731 | N/A | Speed and cost efficiency | Yes | $0.17 in · $0.35 out / 1M |
| Gemini 3.7 Flash | N/A | Google ecosystem integration | No | $1.88 in · $9.38 out / 1M |
Fast variant of the open 2.8T Kimi K3 with 1M context and vision.
Use cases
What it is good for
- 01Autonomous coding agents that navigate and modify large repositories with minimal latency.
- 02Long-document analysis and summarization, including legal contracts, research papers, and financial reports.
- 03Multimodal research workflows combining text, images, and web search for interactive dashboards.
- 04Enterprise automation where data privacy and uncensored reasoning are required.
- 05Real-time planning and decision-making in complex simulations or game development.
Prompting
Getting better results
Use explicit structure in prompts — Kimi K3 Fast excels when given clear goals, steps, and expected output formats.
Leverage function calling and web search for up-to-date information or external tool integration.
Break down long tasks into stages to manage output length within the 131K token limit.
Include image or PDF references directly in prompts for vision-augmented reasoning.
Use JSON schema output for reliable parsing in automated pipelines.
Version history
Predecessor model with smaller context and lower capability.
Base open-weight 2.8T model with 1M context.
Optimized for low-latency inference, same capabilities.
FAQ
Frequently asked questions
Kimi K3 Fast is a low-latency inference variant of Moonshot AI's 2.8-trillion-parameter Kimi K3 model, released on July 27, 2026. It supports a 1-million-token context window, vision input, tool use, and web search, optimized for real-time agentic workflows in coding, research, and planning.
On Venice, Kimi K3 Fast costs $4.50 per million input tokens and $22.50 per million output tokens. Cached input is significantly cheaper at $0.45 per million tokens, making repeated access to long contexts more affordable.
Kimi K3 Fast is not free, but it is based on open weights released by Moonshot AI under an open license. You can access the model via API on Venice, but cannot self-host it directly — the fast-inference variant is served only via API.
Yes. Kimi K3 Fast supports image and PDF input, enabling multimodal reasoning. It can analyze charts, diagrams, and documents, though it only outputs text — it cannot generate or edit images.
Yes. Kimi K3 Fast supports function calling, web search, structured JSON output, and tool use, making it suitable for building autonomous agents that interact with external systems and APIs.
Kimi K3 Fast supports up to 1 million tokens of context, allowing it to process extremely long documents, codebases, or multimodal inputs in a single session. The maximum output length is 131,072 tokens.
Kimi K3 Fast offers open weights, lower cost, and a larger context window, making it better for long-horizon coding and research. Claude Opus 5 excels in safety, enterprise compliance, and nuanced reasoning but is more expensive and closed. Choose K3 Fast for uncensored, private, agentic work; Opus 5 for regulated or safety-critical tasks.
Run Kimi K3 Fast privately
No prompt logging. No data used for training.