Kimi K3 Fast
Kimi K3 Fast is the faster serving path for Moonshot AI's Kimi K3. It trades a higher per-token rate for lower latency, keeps the context window of 1M tokens, and routes through AI Gateway via Fireworks, Morph, Wafer. Your use is subject to Moonshot AI's Terms & Privacy Policies.
import { streamText } from 'ai'
const result = streamText({ model: 'moonshotai/kimi-k3-fast', prompt: 'Why is the sky blue?'})About Kimi K3 Fast
Kimi K3 Fast is the fast serving tier for Kimi K3, Moonshot AI's open-source model for long-horizon engineering work. Released July 27, 2026, Kimi K3 Fast trades a higher per-token cost for lower latency. The model's capabilities don't change.
Everything documented for the base model carries over. Kimi K3 Fast accepts text, image, and video input, supports a context window of 1M tokens, and keeps thinking mode always on. The strengths match too: long-horizon software engineering, knowledge work, deep reasoning, and tasks where code meets visual and spatial reasoning like frontend development, game development, and computer-aided design (CAD).
Two paths reach the fast tier. Set the speed option to fast while keeping the model ID on moonshotai/kimi-k3, and AI Gateway routes to the fast tier and falls back to standard speed when it isn't available. Or call moonshotai/kimi-k3-fast directly, which pins every request to the fast tier without that fallback.
Serving speed counts when someone is waiting. Interactive coding assistants stream output while a developer watches, and edit-run-fix loops repeat many times in a session, so per-turn latency compounds. Batch and offline jobs gain little. Throughput varies with load and context length, so read the live metrics on this page instead of planning around a fixed number.
AI Gateway routes Kimi K3 Fast across Fireworks, Morph, Wafer, including US-based providers for teams with data residency and compliance requirements. To keep inference in US data centers, set inferenceRegion with scope zone and geo region us. Zero Data Retention is configured per request with zeroDataRetention or turned on for every request from AI Gateway dashboard settings, and support varies by provider.
Use the identifier moonshotai/kimi-k3-fast with the AI SDK or any supported interface like Chat Completions, Responses, or Messages. Kimi K3 Fast supports a context window of 1M tokens and completions up to 1M tokens per request, at $4.5 per million input tokens and $22.5 per million output tokens.