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Agents

Voices

List the custom voices in your account and check whether each one is ready to use.

A voice is a voice clone or an imported voice that belongs to your account. These routes return only your own voices, not a shared library. They are read-only, so create and manage voices in the dashboard.

An agent that uses one of these voices shows its ID in voiceCloneId on the agent object. The Calls route also accepts a voiceCloneId.

EndpointRequest
List voicesGET/v1/voices
Get a voiceGET/v1/voices/:id

The voice object

Fields use camelCase. Fields with no value are omitted.

Attributes

idstringrequired
The voice's UUID.
agentIdstring
UUID of the agent linked to this voice.
namestringrequired
The voice's name.
descriptionstring
The voice's description.
cloneTypestringrequired
instant or professional.
sourcestringrequired
clone for a voice trained from an uploaded sample. import for an existing voice added by ID.
statusstringrequired
processing, ready or failed.
languagestring
The voice's language code, such as en or es.
similaritynumber
Similarity setting, on a scale of 0 to 100.
stabilitynumber
Stability setting, on a scale of 0 to 100.
voiceSpeednumber
Speed setting, multiplied by 100. A speed of 1.0 is returned as 100.
processingStartedAtstring
When processing started, as an ISO 8601 timestamp.
processingCompletedAtstring
When processing finished, as an ISO 8601 timestamp.
createdAtstringrequired
When the voice was created, as an ISO 8601 timestamp.
updatedAtstringrequired
When the voice last changed, as an ISO 8601 timestamp.

List voices

GET/v1/voicesread key

Returns your voices, newest first. Deleted voices are left out.

See Pagination.

Query parameters

limitintegerdefault 100
Maximum results, from 1 to 100.
offsetintegerdefault 0
Number of results to skip, up to 1,000,000.
Request
curl https://backend.synthesys.app/api/v1/voices \
  -H "SYNTH_API_KEY: YOUR_API_KEY"
Response
{
  "success": true,
  "data": [
    {
      "id": "9b2d6a10-4c7e-4f3a-a1d5-6e8f0b7c2d91",
      "name": "Support voice",
      "description": "Warm and calm",
      "cloneType": "instant",
      "source": "clone",
      "status": "ready",
      "language": "en",
      "similarity": 75,
      "stability": 50,
      "voiceSpeed": 100,
      "processingStartedAt": "2026-10-02T10:00:00+00:00",
      "processingCompletedAt": "2026-10-02T10:01:30+00:00",
      "createdAt": "2026-10-02T10:00:00+00:00",
      "updatedAt": "2026-10-02T10:01:30+00:00"
    }
  ],
  "pagination": { "total": 1, "limit": 100, "offset": 0 }
}

Get a voice

GET/v1/voices/:idread key

Returns one voice by its UUID.

Returns 404 with Voice clone not found when the voice doesn't exist, was deleted or belongs to another account. An ID that isn't a valid UUID returns 400.

Path parameters

idstringrequired
The voice's UUID.
Request
curl https://backend.synthesys.app/api/v1/voices/9b2d6a10-4c7e-4f3a-a1d5-6e8f0b7c2d91 \
  -H "SYNTH_API_KEY: YOUR_API_KEY"
Response
{
  "success": true,
  "data": {
    "id": "9b2d6a10-4c7e-4f3a-a1d5-6e8f0b7c2d91",
    "name": "Support voice",
    "description": "Warm and calm",
    "cloneType": "instant",
    "source": "clone",
    "status": "ready",
    "language": "en",
    "similarity": 75,
    "stability": 50,
    "voiceSpeed": 100,
    "processingStartedAt": "2026-10-02T10:00:00+00:00",
    "processingCompletedAt": "2026-10-02T10:01:30+00:00",
    "createdAt": "2026-10-02T10:00:00+00:00",
    "updatedAt": "2026-10-02T10:01:30+00:00"
  }
}