Speech

Create speech

post /audio/speech

Generates audio from the input text.

Returns the audio file content, or a stream of audio events.

Body Parameters

• input: string

  The text to generate audio for. The maximum length is 4096 characters.

• model: string or SpeechModel

  One of the available TTS models: tts-1, tts-1-hd, gpt-4o-mini-tts, or gpt-4o-mini-tts-2025-12-15.

  • string

  • SpeechModel = "tts-1" or "tts-1-hd" or "gpt-4o-mini-tts" or "gpt-4o-mini-tts-2025-12-15"

    • "tts-1"

    • "tts-1-hd"

    • "gpt-4o-mini-tts"

    • "gpt-4o-mini-tts-2025-12-15"

• voice: string or "alloy" or "ash" or "ballad" or 7 more or object \{ id \}

  The voice to use when generating the audio. Supported built-in voices are alloy, ash, ballad, coral, echo, fable, onyx, nova, sage, shimmer, verse, marin, and cedar. You may also provide a custom voice object with an id, for example \{ "id": "voice_1234" \}. Previews of the voices are available in the Text to speech guide.

  • string

  • "alloy" or "ash" or "ballad" or 7 more

    • "alloy"

    • "ash"

    • "ballad"

    • "coral"

    • "echo"

    • "sage"

    • "shimmer"

    • "verse"

    • "marin"

    • "cedar"

  • ID object \{ id \}

    Custom voice reference.

    • id: string

      The custom voice ID, e.g. voice_1234.

• instructions: optional string

  Control the voice of your generated audio with additional instructions. Does not work with tts-1 or tts-1-hd.

• response_format: optional "mp3" or "opus" or "aac" or 3 more

  The format to audio in. Supported formats are mp3, opus, aac, flac, wav, and pcm.

  • "mp3"

  • "opus"

  • "aac"

  • "flac"

  • "wav"

  • "pcm"

• speed: optional number

  The speed of the generated audio. Select a value from 0.25 to 4.0. 1.0 is the default.

• stream_format: optional "sse" or "audio"

  The format to stream the audio in. Supported formats are sse and audio. sse is not supported for tts-1 or tts-1-hd.

  • "sse"

  • "audio"

Example

curl https://api.openai.com/v1/audio/speech \
    -H 'Content-Type: application/json' \
    -H "Authorization: Bearer $OPENAI_API_KEY" \
    -d '{
          "input": "input",
          "model": "tts-1",
          "voice": "alloy"
        }'

Example

curl https://api.openai.com/v1/audio/speech \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-4o-mini-tts",
    "input": "The quick brown fox jumped over the lazy dog.",
    "voice": "alloy"
  }' \
  --output speech.mp3

SSE Stream Format

curl https://api.openai.com/v1/audio/speech \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-4o-mini-tts",
    "input": "The quick brown fox jumped over the lazy dog.",
    "voice": "alloy",
    "stream_format": "sse"
  }'

Domain Types

Speech Model

• SpeechModel = "tts-1" or "tts-1-hd" or "gpt-4o-mini-tts" or "gpt-4o-mini-tts-2025-12-15"

  • "tts-1"

  • "tts-1-hd"

  • "gpt-4o-mini-tts"

  • "gpt-4o-mini-tts-2025-12-15"