Guide · Open weights

Is Kimi K3.1 Pro open source?

Kimi K3.1 Pro is an open-weight model, but its weights were not yet downloadable at launch: Moonshot AI says the full model weights will be released by November 4, 2026. The license had not been published as of October 27, 2026. Until then you can use it through Moonshot's apps and API, OpenRouter, or a web chat like this one.

Use Kimi K3.1 Pro now

In short

Moonshot calls K3.1 Pro its most capable open-weight model and promises the full weights by November 4, 2026.
The license terms were not public as of October 27, 2026.
For the open-weight release, Moonshot removed cyber-related training data to limit misuse.
Running a model of about 2.8T parameters yourself needs a multi-GPU server; most people use an API or a hosted chat.

Open weights, not yet released

Moonshot's announcement says the full weights of Kimi K3.1 Pro will be released by November 4, 2026. Open weights means you can download and run the model yourself; whether commercial use is allowed depends on the license, which had not been published when this guide was updated.

Moonshot also says it identified and removed cyber-related data from training for the open-weight release. On its internal exploit benchmark, the shipped model solves 81.0% of tasks against 90.5% for the same pipeline without that removal.

Ways to use Kimi K3.1 Pro today

Until the weights ship, Kimi K3.1 Pro runs only on hosted services.

The official Kimi apps and website, from Moonshot AI.
The Kimi API (kimi-k3.1-pro and kimi-k3.1-pro-highspeed) or OpenRouter (moonshotai/kimi-k3.1-pro).
Independent web chats such as kimi-k31.com, which bill per message.

Is it free?

The model is not free to run: API access costs $2 per 1M input tokens and $10 per 1M output tokens. On this site messages are billed by tokens from 1 credit each, and free credits are available through the daily check-in when it is offered.

Frequently asked questions

When will Kimi K3.1 Pro weights be released?

Moonshot AI says by November 4, 2026. This guide will be updated when they are available.

What license will Kimi K3.1 Pro use?

Moonshot had not published the license as of October 27, 2026. Check the official model release before using the weights commercially.

Can I run Kimi K3.1 Pro locally?

Not yet, because the weights are not out. Once they are, a mixture-of-experts model of about 2.8T total parameters still needs server-class GPUs, even with quantization.

Is kimi-k31.com the official Kimi website?

No. Kimi K3.1 Pro Online is an independent site that sends your messages to Kimi K3.1 Pro through OpenRouter. It is not affiliated with or endorsed by Moonshot AI. The official Kimi apps are at kimi.ai.

Sources

Updated 2026-10-27. Kimi K3.1 Pro Online is an independent site and is not affiliated with or endorsed by Moonshot AI. Kimi is a trademark of its owner. Model replies can be wrong; check important facts and code.