OpenAI API adds 12-hour prompt caching, with cache writes at 2.5x the input price

ChatGPTProduct changeConfirmed

OpenAI added a 12-hour prompt caching option to the Responses API.

It keeps shared instructions, tools and context cached longer to benefit from lower cached-input pricing, even when requests are hours apart.
12-hour cache writes cost 2.5x the input token price.
The changelog did not publish the cached-input rate.

Who can use it: API developers using the v1/responses endpoint. Model coverage was not stated in the changelog entry.
When: Announced October 20, 2026 as available now.

OpenAI API changelog Announced 2026-10-20 · date only

Read the official announcement for access details. Availability can depend on your plan, region or workplace settings.

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