Kimi K3 Is Now Available on FastRouter

Kimi K3 from Moonshot AI is now accessible through FastRouter. It is Moonshot AI's 2.8 trillion parameter flagship multimodal reasoning model, built for long horizon coding, complex knowledge work, visual reasoning, and tool using workflows, with a 1 million token context window.

What Kimi K3 is

Kimi K3 uses Kimi Delta Attention and Attention Residuals to support efficient million token contexts, and always runs in high effort reasoning mode. It accepts text and image input and produces text output, and is exposed through an OpenAI compatible chat completions API, so it drops into the same integration path as every other model on FastRouter.

Where it ranks

On ArtificialAnalysis's Intelligence Index, Kimi K3 scores 57.1. On coding specifically, it scores 76.2. Both put it near the top of the FastRouter catalog on capability, alongside a context window large enough for long document analysis and extended agent loops.

What it is built for

Kimi K3's always-on high effort reasoning mode makes it a fit for tasks where depth matters more than raw speed, long horizon coding sessions, multi-step knowledge work, and visual reasoning tasks that combine image and text input. The tradeoff for that reasoning depth is throughput, at 38 tokens per second it generates text more slowly than lighter, non-reasoning models, which is worth factoring in for latency sensitive applications where output speed is the bottleneck rather than answer quality.

Getting started

Kimi K3 is available through the same FastRouter endpoint as every other model. No additional configuration is required.

1from openai import OpenAI
2
3client = OpenAI(
4    base_url="https://api.fastrouter.ai/api/v1",
5    api_key="<FASTROUTER_API_KEY>",
6)
7
8completion = client.chat.completions.create(
9    model="moonshotai/kimi-k3",
10    messages=[
11        {"role": "user", "content": "Walk through this codebase and map out the module dependencies."}
12    ]
13)
14
15print(completion.choices[0].message.content)
16Replace <FASTROUTER_API_KEY> with your actual FastRouter API key. Install the OpenAI SDK with pip install openai if not already installed.
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Comparing Kimi K3 against other models on FastRouter

The FastRouter Playground makes it straightforward to run the same prompt against Kimi K3 and other models to compare output quality and cost side by side before committing to a routing decision in production.

Custom Evaluations can then be used to validate Kimi K3 against a broader set of production prompts before switching any live traffic to it.

Kimi K3 is available now through FastRouter at fastrouter.ai. One base URL, 160+ models, zero markup on API calls.