Instant Voice Clone (REST API)

Create an instant voice clone via a single POST call. Uploads the audio, runs preprocessing, and returns pre-generated sample clips of the cloned voice — all in one request.

Requirements

• A Smallest AI API key — grab one from the API Keys page.
• A clean audio sample, 5–15 seconds, under 5 MB. Supported types: .mp3, .wav, .mp4, .webm.

$
export SMALLEST_API_KEY=sk_your_key_here

Create the clone

$
curl -X POST "https://api.smallest.ai/waves/v1/voice-cloning" \
>
  -H "Authorization: Bearer $SMALLEST_API_KEY" \
>
  -F "displayName=my-custom-voice" \
>
  -F "file=@/path/to/sample.wav" \
>
  -F "language=en" \
>
  -F "accent=general" \
>
  -F "tags=english,friendly"

Request fields

Response shape

1
{
2
  "message": "Voice clone created successfully",
3
  "data": {
4
    "voiceId": "voice_dLP5T67Qw7",
5
    "displayName": "my-custom-voice",
6
    "status": "completed",
7
    "language": "en",
8
    "model": { "_id": "...", "modelName": "lightning-v3.1" },
9
    "audioFileNames": ["sample.wav"],
10
    "createdAt": "2026-04-20T09:42:17.103Z",
11
    "organizationId": "69561896a37fd214b9a8d33c",
12
    "samples": [
13
      {
14
        "text": "Hello! This is a sample of what I sound like.",
15
        "audioUrl": "https://..."
16
      }
17
    ]
18
  }
19
}

Use data.voiceId directly in any TTS call:

$
curl -X POST "https://api.smallest.ai/waves/v1/lightning-v3.1/get_speech" \
>
  -H "Authorization: Bearer $SMALLEST_API_KEY" \
>
  -H "Content-Type: application/json" \
>
  -d '{
>
    "text": "Hello, this is my cloned voice.",
>
    "voice_id": "voice_dLP5T67Qw7"
>
  }' \
>
  -o output.wav

List your clones

$
curl -H "Authorization: Bearer $SMALLEST_API_KEY" \
>
  "https://api.smallest.ai/waves/v1/voice-cloning"

Returns every clone on your organization along with modelIds (compatible models), status, language, and creation time.

Check model compatibility before using a clone

The modelIds array in the list response tells you which TTS models a clone works with. Check it before passing voice_id to a TTS call:

$
curl -H "Authorization: Bearer $SMALLEST_API_KEY" \
>
  "https://api.smallest.ai/waves/v1/voice-cloning" \
>
  | jq '.data[] | {displayName, voiceId, modelIds}'

1
{ "displayName": "my-voice",   "voiceId": "voice_abc", "modelIds": ["lightning-v3.1"] }
2
{ "displayName": "old-voice",  "voiceId": "voice_xyz", "modelIds": ["lightning-large"] }

Clones created via the current POST /waves/v1/voice-cloning endpoint always produce lightning-v3.1-compatible voices. The older POST /waves/v1/lightning-large/add_voice endpoint (deprecated) only produces lightning-large-compatible voices — those will not work if you try to use them with lightning-v3.1.

Delete a clone

The current public delete endpoint lives at /waves/v1/lightning-large despite the path suggesting otherwise — it deletes any voice clone on your organization regardless of the underlying model.

$
curl -X DELETE "https://api.smallest.ai/waves/v1/lightning-large" \
>
  -H "Authorization: Bearer $SMALLEST_API_KEY" \
>
  -H "Content-Type: application/json" \
>
  -d '{ "voiceId": "voice_dLP5T67Qw7" }'

Errors

Migrating from the legacy endpoint

If you’re currently using POST /waves/v1/lightning-large/add_voice, switch to POST /waves/v1/voice-cloning:

• Same auth — Authorization: Bearer $SMALLEST_API_KEY.
• Same multipart shape for displayName + file.
• New optional fields — language, description, accent, tags.
• Response includes samples — pre-generated audio clips of the cloned voice, which the legacy endpoint did not provide.
• Default model is lightning-v3.1 — the new unified TTS model. Voices cloned via the legacy endpoint only worked on lightning-large and returned empty audio on lightning-v3.1.

The legacy endpoint still works but is marked deprecated in the API reference.

Need help? Email support@smallest.ai or ask on Discord.