Kimi K2 0905 is Moonshot AI's September 2025 K2 checkpoint, a refined release focused on agentic coding workflows with a context window of 262.1K tokens, available through AI Gateway via baseten, fireworks, groq, moonshotai.
import { streamText } from 'ai'
const result = streamText({ model: 'moonshotai/kimi-k2-0905', prompt: 'Why is the sky blue?'})Kimi K2 0905 carries a date stamp (September 5, 2025), following Moonshot AI's convention of identifying checkpoints by release date. The 0905 release is a distinct checkpoint from the original K2, not a silent in-place update.
The context window of 262.1K tokens is the main structural change. Agentic coding sessions accumulate context quickly: task descriptions, file contents, tool outputs, reasoning steps, and error messages stack up over many turns. The window of 262.1K tokens keeps an entire project-scale context in scope without truncation. This matters when an agent reviews multiple files, runs tests, and iterates on fixes across a long session.
For teams already using the base K2, the 0905 checkpoint is a drop-in upgrade. It brings training refinements and the extended context window. The API interface, tool-calling format, and integration patterns stay the same. Switch by updating the model string to moonshotai/kimi-k2-0905.
The narrower provider set is the main operational difference. This checkpoint routes across baseten, fireworks, groq, moonshotai, while the base K2 covers a wider set. Weigh that against the 0905 training improvements if you need the largest failover coverage.
Kimi K2 0905 is available through AI Gateway at $1.0 per million input tokens and $3.0 per million output tokens.