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Kimi K2 0905

MoonshotAI | 262,144 token context | $0.60/M input, $2.50/M output. Kimi K2 0905 is the September update of Kimi K2 0711. It is a large-scale Mixture-of-Experts (MoE) language model developed by Moonshot AI, featuring 1 trillion total parameters with 32 billion active per forward pass. It supports long-context inference up to 256k tokens, extended from the previous 128k. This update improves agentic coding with higher accuracy and better generalization across scaffolds, and enhances frontend coding with more aesthetic and functional outputs for web, 3D, and related tasks. Kimi K2 is optimized…MoonshotAI | 262,144 token context | $0.60/M input, $2.50/M output. Kimi K2 0905 is the September update of Kimi K2 0711. It is a large-scale Mixture-of-Experts (MoE) language model developed by Moonshot AI, featuring 1 trillion total parameters with 32 billion active per forward pass. It supports long-context inference up to 256k tokens, extended from the previous 128k. This update improves agentic coding with higher accuracy and better generalization across scaffolds, and enhances frontend coding with more aesthetic and functional outputs for web, 3D, and related tasks. Kimi K2 is optimized for agentic capabilities, including advanced tool use, reasoning, and code synthesis. It excels across coding (LiveCodeBench, SWE-bench), reasoning (ZebraLogic, GPQA), and tool-use (Tau2, AceBench) benchmarks. The model is trained with a novel stack incorporating the MuonClip optimizer for stable large-scale MoE training.

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Kimi K2 0905 is the September 2025 update of Moonshot AI's trillion-parameter MoE model, with 32 billion parameters active per forward pass and a 256k-token context window. The update sharpens agentic coding and frontend work, and the weights are open. It suits developers who want a serious coding agent they can self-host or run cheaply via API.

Known for

  • Strong agentic coding: competitive on SWE-Bench verified and SWE-Bench Multilingual.
  • Open weights on Hugging Face — you can download and run it yourself.
  • 256k context window, doubled from the previous 128k release.
  • Improved frontend coding: better aesthetics and function for web and 3D tasks.
  • Tool use and reasoning built in, not bolted on.

Watch out for

  • 1 trillion total parameters means local deployment demands serious hardware; most users will hit the API.
  • Output is priced at $2.50/M tokens — not expensive, but longer agentic runs add up fast.
  • Moonshot AI has not published the licence terms prominently; check the repo before building a product on it.

Prompts to try

Fix a real bug
Here is a Python function that is supposed to parse a nested JSON config and return a flat dict of dot-separated keys and their values. It silently drops keys when a value is an empty list. Identify the bug, explain why it happens, and return a corrected version with a test that would have caught it. ```python def flatten(d, prefix=''): out = {} for k, v in d.items(): key = f'{prefix}.{k}' if prefix else k if isinstance(v, dict): out.update(flatten(v, key)) elif v: out[key] = v return out ```
Build a small web component
Write a self-contained HTML file with no external dependencies that renders an interactive kanban board with three columns: To Do, In Progress, Done. Cards should be draggable between columns using the HTML drag-and-drop API. Style it cleanly with inline CSS. Add a small form at the top to create a new card with a title.
Plan a multi-step agent task
You are a coding agent with access to a bash terminal and a file editor. A user's Node.js project fails its CI pipeline because three tests import a module that no longer exists after a recent refactor. Describe the exact sequence of tool calls you would make — what you read first, how you trace the broken imports, and how you decide what to write — before touching any file.

Compare with

  • Kimi K3
    Open-weights model
    1,048,576 token context · $0.30/M input, $11.94/M output
  • Kimi K2 Thinking
    Open-weights model
    262,144 token context · $0.60/M input, $2.50/M output
  • Kimi K2.7 Code
    Open-weights model
    262,144 token context · $0.67/M input, $3.35/M output
  • Kimi K2.5
    Open-weights model
    262,144 token context · $0.50/M input, $2.50/M output
More text models from moonshotai

Questions people ask

Are the weights open and can I run Kimi K2 0905 locally?
Yes, the weights are published on Hugging Face under moonshotai/Kimi-K2-Instruct-0905. With 1 trillion total parameters you will need substantial hardware to run it at full precision; most people will use a quantized version or the API.
What does Kimi K2 0905 cost and what is the context window?
Via API it is $0.60 per million input tokens and $2.50 per million output tokens, with a 256k-token context window.
How does the 0905 update differ from the original Kimi K2?
The September update improves agentic coding accuracy and generalisation across different scaffolds, strengthens frontend coding output, and extends the context window from 128k to 256k tokens.
Captain's verdict
A capable open-weights coding agent at a reasonable API price — the 256k context and agentic improvements make the September update worth the switch.
Model card on Hugging Face
Captain writes these notes from the model's own description and model card. Prices and context sizes are the provider's at the time of writing and can change.
Ranking badge
Updated Oct 22, 2026
Kimi K2 0905 on ModelTrends.ai: Heat 1,748°
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