MoonshotAI: Kimi K2.5

This row had a death date on it, which almost none do: only a handful of the several hundred rows in the OpenRouter catalog carry a non-null expiration_date at any given time — a count and a membership that shift from one snapshot to the next — and this one's date has since come due: Moonshot's platform record reads 2026-08-31source, accessed 2026-09-01, and the vendor's model list has now moved to the past tense — "kimi-k2.5 and the moonshot-v1 series were officially retired on August 31, 2026. Calls to these models now return a 404 (model not found) error" — pointing migrations at kimi-k3.

The catalog reads this row active; this page reads it deprecated, and the disagreement is which signal counts. OpenRouter cleared the expiry from its own row, not publishedopenrouter-models, last checked 2026-09-14, and the catalog's status is derived from that field — a cleared expiry reads active. The deprecated badge follows Moonshot's own documentation, which files kimi-k2.5 under "Deprecated Models" — "officially discontinued on August 31, 2026 and is no longer maintained or supported". The router's data stopped carrying a date; the vendor's page says the model is discontinued. The row still lists at $0.45per million tokensopenrouter-models, last checked 2026-09-14 in and $2.25per million tokensopenrouter-models, last checked 2026-09-14 out — but this page does not assert that a call through it would succeed; confirming that needs a credentialed call nobody here made.

The arithmetic is the story. Released 27 January 2026, off the vendor's platform on 31 August: 216 days of service for a model that shipped as a trillion-parameter flagship, continually pretrained on roughly 15 trillion mixed image and text tokens on top of Kimi-K2-Base, and topped the tool-using HLE-Full evaluation — though not the plain one — on the day it launched. The model card lists the split: 50.2 on HLE-Full with tools, and 30.1 on the plain variant, where Gemini 3 Pro's 37.5 is the top of the table. Its replacement in the same family, moonshotai/kimi-k3, arrived on 16 July — 170 days after it.

What actually ends on 31 August is an endpoint, not a model. K2.5's weights were published under a Modified MIT License and stay downloadable after the API stops answering, so the retirement withdraws Moonshot's hosting and nothing else: anyone with the hardware can keep serving the same checkpoint. That is the practical difference between an open-weight retirement and a closed one. For a closed model the sunset date is the date the artefact becomes unreachable to everyone; here it is the date one company stops paying for the GPUs.