What Is Kimi K3? Moonshot AI's New Flagship Model Explained

What Is Kimi K3? Moonshot AI's New Flagship Model Explained

Kimi K3 is Moonshot AI's new flagship large language model, released the week of July 14, 2026. It replaces K2.5 as the company's top-tier model, and Moonshot is positioning it around long-horizon coding, knowledge work, and deep reasoning rather than chat.

This guide covers what K3 actually is: the specs Moonshot has published, how it differs from the rest of the K-series lineup, how to access it, and what's still unknown, including pricing and independent benchmarks.

TL;DR

• Kimi K3 launched the week of July 14, 2026, per Moonshot AI's own announcement. Coverage differs by a few days on the exact date, so treat "mid-July 2026" as the safe window.
• 2.8 trillion parameters, a 1 million token context window, and a maximum output of 131,072 tokens.
• Natively multimodal: text, images, and video.
• Uses MXFP4 quantization.
• K3 is not open-weight. Moonshot's latest open release remains K2.5; there is no K3 repository on the company's GitHub.
• Access is via API at api.moonshot.cn/v1, in an OpenAI-compatible request format.
• Pricing is not fully public. Moonshot lists separate input and output token rates but hasn't published the exact per-token numbers. File operations are "temporarily free."
• No official K3 benchmark suite has been published yet. Don't trust any benchmark number you see attributed to K3 right now, including on this site.

What Is Kimi K3?

Kimi K3 is the new flagship model in Moonshot AI's Kimi lineup, sitting above K2.7 Code and K2.6. Moonshot positions it for long-horizon coding, knowledge work, and deep reasoning: tasks that require sustained context and multi-step follow-through rather than single-turn chat replies.

The model is large: Moonshot and Hugging Face both list K3 at 2.8 trillion parameters. It ships with a 1 million token context window and a maximum output of 131,072 tokens per response, according to Moonshot's own API documentation. K3 is also natively multimodal, handling text, images, and video inputs directly rather than through a separate vision adapter, per Moonshot's overview docs.

On the technical side, K3 uses MXFP4 quantization, a detail Moonshot and Hugging Face published alongside the release.

The K-Series Lineup: Where K3 Fits

K3 is the flagship, but it isn't Moonshot's only current model. As of this writing, the active lineup is:

K2.5 matters for a specific reason: it's the newest model Moonshot has actually open-sourced. K3 is not on github.com/moonshotai, and there's no indication yet that it will be. If open weights matter for your use case, K2.5 (not K3) is the model to look at today.

Is Kimi K3 Open-Weight?

No. K3 is closed. Moonshot has not published K3's weights, and there's no K3 repository on the company's GitHub. This is a real shift from the framing some outlets have used around Moonshot's China-based, open-source-friendly reputation. K2.5 remains the company's most recent open release, and K3 sits apart from it as an API-only flagship.

How to Access Kimi K3

K3 is available through Moonshot's API. The base URL is api.moonshot.cn/v1, and the request format is OpenAI-compatible, so if you already have code that talks to an OpenAI-style chat completions endpoint, adapting it is mostly a matter of changing the base URL, API key, and model name rather than rewriting your integration.

from openai import OpenAI

client = OpenAI(
    base_url="https://api.moonshot.cn/v1",  # Moonshot's OpenAI-compatible endpoint
    api_key="YOUR_MOONSHOT_API_KEY",
)

response = client.chat.completions.create(
    model="kimi-k3",  # confirm the exact model string in your Moonshot console
    messages=[
        {"role": "user", "content": "Summarize this document and flag any open questions."},
    ],
)

print(response.choices[0].message.content)

Because the interface mirrors OpenAI's, most existing SDKs and tooling built for OpenAI-compatible APIs should work with only configuration changes. Confirm the exact model identifier string in your own Moonshot console before shipping, since Moonshot hasn't published a single canonical model name in its public docs at the time of writing.

Kimi K3 Pricing: What's Actually Known

Here's where we have to be honest about the gap. Moonshot's pricing page lists separate input and output token pricing for K3, and notes that file operations are "temporarily free." What it doesn't list is the exact per-token rate.

We are not going to invent a number. Until Moonshot publishes exact rates, treat K3 pricing as unknown. One data point worth flagging: Pingwest, a China-focused tech outlet, characterized K3 as "very strong, very expensive." That's Pingwest's own characterization, not a confirmed price point, and we're citing it as their view rather than our claim.

If you need firm numbers to budget against, wait for Moonshot's official rate card rather than estimating from early coverage.

Are There Kimi K3 Benchmarks?

No official benchmark suite for K3 has been published as of this writing. That matters because K3 is entering a news cycle full of comparison claims ("kimi k3 vs claude fable 5," "kimi k3 vs gpt-5.6"), and none of them can currently point to a verified, apples-to-apples number for K3.

Anywhere you see a specific K3 benchmark score right now, including comparisons against Claude Fable 5, GPT-5.6, or anything else, treat it as unverified until Moonshot or an independent evaluator publishes one. We're not citing any K3 benchmark number in this post for that reason. See our Kimi K3 vs Claude Fable 5 comparison for how we handle that gap when the comparison question comes up directly.

Why Kimi K3 Is Getting Attention

Coverage of K3 has clustered around a few angles. Forbes framed the launch as a "will it challenge OpenAI and Anthropic" story. TechCrunch's framing has been more skeptical in tone ("threat or menace"). There's also a Chinese AI independence narrative running through coverage, and Yahoo Finance reported the launch putting pressure on AMD's stock. We're not able to independently verify the stock-pressure claim's mechanics here; we're noting it as a reported media angle, not a financial analysis of our own.

Bottom Line

Kimi K3 is a real, large, natively multimodal flagship model from Moonshot AI, with a 1 million token context window and specs that put it in serious flagship territory on paper. What it isn't, yet, is fully priced or independently benchmarked. The honest state of play in mid-July 2026: strong specs, a closed-weights model (K2.5 stays the open option), an OpenAI-compatible API you can start testing today, and two open questions, price and performance, that neither Moonshot nor anyone else has fully answered in public yet.

If you're evaluating K3 against Claude's current flagship, see our Kimi K3 vs Claude Fable 5 breakdown, and for the full picture of Anthropic's lineup, our model comparison hub.

FAQ

When was Kimi K3 released? The week of July 14, 2026. Moonshot AI's own homepage points to July 14, while China Money Network's coverage cites July 17. Given the discrepancy, "mid-July 2026" or "the week of July 14" is the accurate way to describe the timing without picking a single exact day.

How many parameters does Kimi K3 have? 2.8 trillion, per Moonshot AI and a Hugging Face blog post accompanying the release.

What is Kimi K3's context window? 1 million tokens for input context, with a maximum output of 131,072 tokens per response, according to Moonshot's API documentation.

Is Kimi K3 open-source? No. K3 is not open-weight and is not published on Moonshot's GitHub. Kimi K2.5 remains Moonshot's most recent open-weight release.

How much does Kimi K3 cost? Exact per-token pricing has not been published. Moonshot's pricing page confirms separate input and output rates exist and that file operations are temporarily free, but doesn't list the numbers. Treat any specific price you see elsewhere as unconfirmed until Moonshot publishes a rate card.

Are there Kimi K3 benchmarks? No official benchmark suite has been published yet. Any K3 benchmark number circulating right now, including in comparison posts, should be treated as unverified.

How do I access Kimi K3? Through Moonshot's API at api.moonshot.cn/v1, using an OpenAI-compatible request format. You'll need a Moonshot API key from their developer console.

Sources

• Moonshot AI homepage (moonshot.ai), K3 launch announcement
• China Money Network, K3 coverage (July 17, 2026)
• Moonshot AI + Hugging Face blog, K3 model card (parameters, quantization)
• platform.kimi.com/docs/api/chat (context window, max output)
• platform.kimi.com/docs/overview (multimodal capabilities)
• platform.kimi.com/pricing (pricing structure)
• github.com/moonshotai (open-weight release history)
• Pingwest, K3 pricing characterization
• Forbes, TechCrunch, Yahoo Finance (media coverage angles)