OpenAI: GPT-4o Mini TTS – API Quickstart

Sample code and API for GPT-4o Mini TTS

OpenRouter normalizes requests and responses across providers for you.

Get your API key

Create an API key from your OpenRouter dashboard and set it as an environment variable:

Make your first request

Use openai/gpt-4o-mini-tts-2025-12-15 with the OpenRouter API:

OpenRouter provides a text-to-speech API that converts text into natural-sounding audio. Send text and a voice selection, and receive raw audio bytes in your chosen format.

The response is a raw audio stream (not JSON). The generation ID is returned in the X-Generation-Id response header for tracking.

Using third-party SDKs

For information about using third-party SDKs and frameworks with OpenRouter, please see our frameworks documentation.

Endpoint

POSThttps://openrouter.ai/api/v1/audio/speech

AuthorizationBearer $OPENROUTER_API_KEY

Content-Typeapplication/json

HTTP-Refereroptional — your site URL, for rankings

X-Titleoptional — your site name, for rankings

Modelopenai/gpt-4o-mini-tts-2025-12-15

Parameters

Name	Type	Default	Description
`seed`	integer	—	If specified, the inferencing will sample deterministically, such that repeated requests with the same seed and parameters should return the same result.
`max_tokens`	integer	—	This sets the upper limit for the number of tokens the model can generate in response.
`response_format`	map	—	Forces the model to produce specific output format.
`structured_outputs`	boolean	—	If the model can return structured outputs using response_format json_schema.
`temperature`	float	`1`	This setting influences the variety in the model's responses.
`top_p`	float	`1`	This setting limits the model's choices to a percentage of likely tokens: only the top tokens whose probabilities add up to P.
`stop`	array	—	Stop generation immediately if the model encounter any token specified in the stop array.
`frequency_penalty`	float	`0`	This setting aims to control the repetition of tokens based on how often they appear in the input.
`presence_penalty`	float	`0`	Adjusts how often the model repeats specific tokens already used in the input.
`logit_bias`	map	—	Accepts a JSON object that maps tokens (specified by their token ID in the tokenizer) to an associated bias value from -100 to 100.
`logprobs`	boolean	—	Whether to return log probabilities of the output tokens or not.
`top_logprobs`	integer	—	An integer between 0 and 20 specifying the number of most likely tokens to return at each token position, each with an associated log probability.