> ## Documentation Index
> Fetch the complete documentation index at: https://docs.apiyi.com/llms.txt
> Use this file to discover all available pages before exploring further.

# New FAQ: OpenAI Fast / Ultrafast Mode Not Yet Supported

> A new FAQ explains that APIYI does not yet support OpenAI service_tier levels (fast, ultrafast, priority, flex). Requests with the parameter do not error and run and bill at the standard tier.

**2026/10/22 14:37 (UTC+8)** · Docs Update · OpenAI

📖 **New FAQ: APIYI does not yet support OpenAI Fast / Ultrafast mode**

Requests that include `service_tier` (`fast`, `ultrafast`, `priority`, `flex`) do not error, but they run at the standard tier: speed is unchanged, billing uses the standard price, and `/v1/responses` returns `default`. Sending it never costs extra, so no code change is needed.

See [Does APIYI Support OpenAI Fast / Ultrafast Mode?](/en/faq/openai-service-tier-fast-mode)

***

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