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The fastrun API follows OpenAI’s API. Requests and responses have the same shape, so OpenAI SDKs and tools work with only the base URL, key and model changed.

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Base URL

HTTPS only, TLS 1.2 or later.

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Authentication

Send your API key as a bearer token. See Authentication.

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Endpoints

Other OpenAI endpoints, such as embeddings, images and the Responses API, are not supported.

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Requests

  • Send JSON with Content-Type: application/json. Bodies can be up to 64 MiB.
  • A streamed request can run for up to 60 minutes; one without streaming must be complete within 10 minutes. See Timeouts.
  • Errors use OpenAI’s error format; see Errors and retries.

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Differences from OpenAI

  • Model IDs are fastrun’s; see Models.
  • Input is text only.
  • Reasoning text comes in message.reasoning (and delta.reasoning when streaming). See Reasoning.
  • Extra sampling parameters are accepted: top_k, min_p, repetition_penalty and chat_template_kwargs.