Voice Cloning

The Voices API lets you list the voices available to your account, clone a new voice from an audio or video sample, and delete clones you no longer need. A cloned voice returns a voiceId that you reuse anywhere a voice is accepted — in POST /v2/tts and in text inputs on POST /v2/generate.

The headline flow: clone a speaker’s voice from a talking-head video, synthesize a brand-new line in that voice, then lip sync the result onto a different video — all on a single API key. See The flagship flow below.

Listing voices

GET /v2/voices returns every voice available to you: sync. labs’ built-in voices plus any clones you have created. Use a voice’s id as the voiceId in text-to-speech and in generation text inputs.

curl https://api.sync.so/v2/voices \
  -H "x-api-key: $SYNC_API_KEY"

The response is an array of voice objects:

[
  {
    "id": "EXAVITQu4vr4xnSDxMaL",
    "name": "Rachel",
    "provider": "elevenlabs",
    "previewUrl": "https://assets.sync.so/voices/rachel-preview.mp3"
  }
]

During a provider outage, the voices endpoint can return the last complete list, up to 24 hours old, with x-sync-voices-stale: true. New or changed voices may be missing. A lookup for an ID absent from that saved list returns 503 rather than 404. Retry after the service recovers.

Cloning a voice

POST /v2/voices clones a new voice from a sample and returns a voiceId you can use immediately. Provide a name and exactly one sample source: a sync. labs-hosted url, an assetId, or sampleUrls with 1–10 sync. labs-hosted URLs.

Both audio and video sources are supported. For video sources, the audio track is extracted automatically and the first 2 minutes are used for cloning.

Clone from an uploaded asset

The recommended path: upload the sample with the Asset Uploads flow, then clone from the returned assetId.

curl -X POST https://api.sync.so/v2/voices \
  -H "x-api-key: $SYNC_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Founder voice",
    "assetId": "asset_abc123"
  }'

Clone from a hosted URL

If your sample already lives in sync. labs storage, pass its url instead of an assetId.

curl -X POST https://api.sync.so/v2/voices \
  -H "x-api-key: $SYNC_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Founder voice",
    "url": "https://assets.sync.so/uploads/founder-sample.mp4"
  }'

Clone from several recordings

Use sampleUrls to combine recordings of the same speaker into one voice. Video samples have their audio extracted automatically.

{
  "name": "Narrator",
  "provider": "elevenlabs",
  "sampleUrls": [
    "https://assets.sync.so/uploads/narrator-1.mp3",
    "https://assets.sync.so/uploads/narrator-2.mp4"
  ]
}

Use URLs returned by your own asset uploads. Provide exactly one of url, assetId, or sampleUrls.

Request body

Response

A 201 response returns the new voice:

{
  "voiceId": "cloned_9f8e7d6c",
  "name": "Founder voice",
  "id": "550e8400-e29b-41d4-a716-446655440000"
}

Deleting a voice

Deleting a cloned voice removes it for everyone in your organization and cannot be undone. In Studio, select Delete from the voice’s actions menu and confirm.

A 409 means the voice is still being cloned. Wait for cloning to finish. A 503 elevenlabs_service_unavailable means deletion failed and the voice is kept; retry later.

DELETE /v2/voices/{id} removes a clone and frees a clone slot. Use the Sync UUID in the clone response’s id field; voiceId identifies the provider voice.

curl -X DELETE https://api.sync.so/v2/voices/550e8400-e29b-41d4-a716-446655440000 \
  -H "x-api-key: $SYNC_API_KEY"

A 200 response confirms the voice was deleted and the slot is available for a new clone.

The flagship flow

Clone a voice from a talking-head video, synthesize a new line in that voice with text-to-speech, then lip sync that audio onto a different video. The entire pipeline runs on one API key.

curl -X POST https://api.sync.so/v2/voices \
  -H "x-api-key: $SYNC_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Speaker clone",
    "assetId": "asset_talkinghead"
  }'

curl -X POST https://api.sync.so/v2/tts \
  -H "x-api-key: $SYNC_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "voiceId": "cloned_9f8e7d6c",
    "script": "Here is a brand new line, spoken in my own voice."
  }'

curl -X POST https://api.sync.so/v2/generate \
  -H "x-api-key: $SYNC_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "lipsync-2",
    "input": [
      { "type": "video", "url": "https://assets.sync.so/uploads/target-video.mp4" },
      { "type": "audio", "url": "https://assets.sync.so/tts/synthesized-line.wav" }
    ],
    "options": { "sync_mode": "cut_off" }
  }'

The end-to-end version of this pipeline in Python and TypeScript:

import time
from sync import Sync
from sync.common import Audio, GenerationOptions, Video
sync = Sync()
# 1. Clone the voice from a talking-head video already in sync. labs storage
voice = sync.voices.clone(
    name="Speaker clone",
    asset_id="asset_talkinghead",
)
# 2. Synthesize a new line in the cloned voice
tts = sync.tts.create(
    voice_id=voice.voice_id,
    script="Here is a brand new line, spoken in my own voice.",
)
synthesized_audio_url = tts.synthesized_audio_url
# 3. Lip sync that audio onto a different video
response = sync.generations.create(
    input=[
        Video(url="https://assets.sync.so/uploads/target-video.mp4"),
        Audio(url=synthesized_audio_url),
    ],
    model="lipsync-2",
    options=GenerationOptions(sync_mode="cut_off"),
)
job_id = response.id
generation = sync.generations.get(job_id)
while generation.status not in ["COMPLETED", "FAILED", "REJECTED"]:
    time.sleep(10)
    generation = sync.generations.get(job_id)
if generation.status == "COMPLETED":
    print(f"Video ready: {generation.output_url}")

FAQ

Related

• Text-to-Speech — synthesize speech with a cloned voiceId.
• Asset Uploads — upload local audio or video into sync. labs storage before cloning.
• Voices API reference — full request and response schemas for list, clone, and delete.