Skip to main content
Azure Speech is an Azure AI Speech text-to-speech provider. In OpenClaw it synthesizes outbound reply audio as MP3 by default, native Ogg/Opus for voice notes, and 8 kHz mulaw audio for telephony channels such as Voice Call. OpenClaw uses the Azure Speech REST API directly with SSML and sends the provider-owned output format through X-Microsoft-OutputFormat.
DetailValue
WebsiteAzure AI Speech
DocsSpeech REST text-to-speech
AuthAZURE_SPEECH_KEY plus AZURE_SPEECH_REGION
Default voiceen-US-JennyNeural
Default file outputaudio-24khz-48kbitrate-mono-mp3
Default voice-note fileogg-24khz-16bit-mono-opus

​
Getting started

1

Create an Azure Speech resource

In the Azure portal, create a Speech resource. Copy KEY 1 from Resource Management > Keys and Endpoint, and copy the resource location such as eastus.
AZURE_SPEECH_KEY=<speech-resource-key>
AZURE_SPEECH_REGION=eastus
2

Select Azure Speech in messages.tts

{
  messages: {
    tts: {
      auto: "always",
      provider: "azure-speech",
      providers: {
        "azure-speech": {
          voice: "en-US-JennyNeural",
          lang: "en-US",
        },
      },
    },
  },
}
3

Send a message

Send a reply through any connected channel. OpenClaw synthesizes the audio with Azure Speech and delivers MP3 for standard audio, or Ogg/Opus when the channel expects a voice note.

​
Configuration options

OptionPathDescription
apiKeymessages.tts.providers.azure-speech.apiKeyAzure Speech resource key. Falls back to AZURE_SPEECH_KEY, AZURE_SPEECH_API_KEY, or SPEECH_KEY.
regionmessages.tts.providers.azure-speech.regionAzure Speech resource region. Falls back to AZURE_SPEECH_REGION or SPEECH_REGION.
endpointmessages.tts.providers.azure-speech.endpointOptional Azure Speech endpoint/base URL override.
baseUrlmessages.tts.providers.azure-speech.baseUrlOptional Azure Speech base URL override.
voicemessages.tts.providers.azure-speech.voiceAzure voice ShortName (default en-US-JennyNeural).
langmessages.tts.providers.azure-speech.langSSML language code (default en-US).
outputFormatmessages.tts.providers.azure-speech.outputFormatAudio-file output format (default audio-24khz-48kbitrate-mono-mp3).
voiceNoteOutputFormatmessages.tts.providers.azure-speech.voiceNoteOutputFormatVoice-note output format (default ogg-24khz-16bit-mono-opus).

​
Notes

Azure Speech uses a Speech resource key, not an Azure OpenAI key. The key is sent as Ocp-Apim-Subscription-Key; OpenClaw derives https://<region>.tts.speech.microsoft.com from region unless you provide endpoint or baseUrl.
Use the Azure Speech voice ShortName value, for example en-US-JennyNeural. The bundled provider can list voices through the same Speech resource and filters voices marked deprecated or retired.
Azure accepts output formats such as audio-24khz-48kbitrate-mono-mp3, ogg-24khz-16bit-mono-opus, and riff-24khz-16bit-mono-pcm. OpenClaw requests Ogg/Opus for voice-note targets so channels can send native voice bubbles without an extra MP3 conversion.
azure is accepted as a provider alias for existing PRs and user config, but new config should use azure-speech to avoid confusion with Azure OpenAI model providers.

Text-to-speech

TTS overview, providers, and messages.tts config.

Configuration

Full config reference including messages.tts settings.

Providers

All bundled OpenClaw providers.

Troubleshooting

Common issues and debugging steps.