AI model guide
Kimi K3.1: What It Is, What It Costs, How to Use It
Kimi K3.1 refers to Moonshot AI’s K3.1 model series, led by Kimi K3.1 Pro—a multimodal flagship aimed at long-horizon coding, 3D creation, financial research, and agent workflows. It advertises a 1-million-token context window and is available in Kimi consumer products and via the Kimi API (including a faster Highspeed variant). This page summarizes what it is, API pricing, how to start, and how to evaluate it against alternatives. Always verify details on official Moonshot / Kimi pages.
Note: Product names in marketing often say “Kimi K3.1”; the API model IDs are typically kimi-k3.1-pro and kimi-k3.1-pro-highspeed. Reviewed against official Kimi sources on (Asia/Shanghai).
What Kimi K3.1 is
- Vendor: Moonshot AI (月之暗面); product brand Kimi.
- Flagship model: Kimi K3.1 Pro — described as a 3T-class model with native visual understanding and an announced open-weight release.
- Context: ~1M tokens (1,048,576) on Pro and Highspeed, per official model docs.
- Strengths called out by the vendor: coding agents, 3D / creative front-end work, financial research, long agent runs.
- Surfaces: Kimi web/apps, Kimi Work, Kimi Code, and Kimi API.
- Highspeed variant: same series, roughly 2–3× faster responses at higher API rates.
Pricing
API figures below are public USD rates per 1M tokens as listed on Kimi resources around late October 2026. Membership / consumer plans differ. Verify on the official site before you buy or ship to production.
| Model ID | Input / MTok | Output / MTok | Notes |
|---|---|---|---|
kimi-k3.1-pro |
$2.00 | $10.00 | The same rate applies across the context window; caching has separate rates. |
kimi-k3.1-pro-highspeed |
$4.00 | $20.00 | Faster responses at a higher token price; the speed estimate is a vendor claim. |
| Kimi membership / chat | Plan-based (varies by region) | Membership benefits and API usage are billed separately. | |
How to get started
-
Try it in the Kimi app
Open kimi.com or your regional Kimi / Moonshot entry, sign in, and start a new chat. Prefer K3.1 Pro when the model picker is available.
-
Create an API key
Go to the Kimi K3.1 Pro quickstart, create or top up an API account if required for flagship models, and generate a key.
-
Call the model ID
Use
kimi-k3.1-profor cost-sensitive long jobs, orkimi-k3.1-pro-highspeedwhen latency matters. Enable streaming, tools, or vision only as your stack needs. -
Run a small eval
Test one coding task, one long-document summary, and one tool-using agent flow against your current GPT/Claude baseline before migrating traffic.
How Kimi K3.1 compares
GPT and Claude are useful alternatives to evaluate alongside Kimi. Use the same documents and tasks; model names alone do not establish which option is best.
| Area | Question | Suggested test |
|---|---|---|
| Long documents | Can it find and cite the relevant passage? | Ask the same questions about a document you can verify. |
| Coding | Does the result work in your codebase? | Run the same change request and check the resulting behavior. |
| Cost and speed | What does a completed task cost? | Record token usage, caching, elapsed time, and retries. |
Official sources
Reviewed October 31, 2026 against the official launch announcement and API platform. Vendor capability claims are not independent test results. API billing is separate from consumer membership.
- Kimi K3.1 Pro tech blog
- Kimi K3.1 Pro pricing overview
- Kimi API — K3.1 Pro quickstart
- Kimi API model list
- Kimi product (kimi.com)
- Moonshot AI (moonshot.cn)
FAQ
What is Kimi K3.1?
Kimi K3.1 usually means Moonshot AI’s K3.1 series, led by Kimi K3.1 Pro—a multimodal flagship with roughly 3T-class scale, native vision, and a 1M-token context window for coding, 3D creation, financial research, and agent tasks.
Who makes Kimi K3.1?
Moonshot AI (月之暗面) builds Kimi. K3.1 Pro ships in Kimi consumer products and on the Kimi API platform; regional entry points include kimi.com and Moonshot properties.
How much does the Kimi K3.1 Pro API cost?
Public rates around late October 2026 list about $2 / $10 per million input/output tokens for kimi-k3.1-pro, and about $4 / $20 for Highspeed, plus cache tiers. Re-check the official pricing page before you budget.
What is the context window?
Official documentation describes a 1,048,576-token context window for Pro and Highspeed, with flat per-token pricing (no separate context-length price bands called out for these IDs).
What is Kimi K3.1 Pro Highspeed?
It is the faster API sibling of K3.1 Pro—roughly 2–3× speed at higher token prices. Use it for interactive work; keep standard Pro when throughput cost dominates.
Is Kimi K3.1 open weight?
The launch materials stated full Pro weights would be released (vendor target around November 4, 2026). Check the download location and license on Moonshot / Kimi channels when you need weights.
How do I try it without writing code?
Use the Kimi web or mobile apps, sign in, and select K3.1 Pro if offered. Feature access may depend on membership or enterprise toggles—check the in-product model list.
How do I call it from an API?
Create credentials on platform.kimi.ai, complete any required top-up for flagship models, then send requests to kimi-k3.1-pro or kimi-k3.1-pro-highspeed following the official quickstart (streaming, tools, vision).
How does it compare to GPT or Claude?
K3.1 Pro emphasizes long context plus coding/agent workloads from Moonshot AI. GPT and Claude remain strong proprietary generalists. Compare with your own evals; vendor scoreboards alone are not enough.
Is this page affiliated with Moonshot or Kimi?
No. This is an independent FAQ-style guide. Confirm pricing, terms, and availability on official Moonshot / Kimi sites before purchasing or integrating.
Updated (Asia/Shanghai). Not affiliated with Moonshot AI, Kimi, OpenAI, or Anthropic.