# Inworld Instant Voice Cloning (slim)

> Inworld's Instant Voice Cloning API makes a reusable text-to-speech voice from 3 to 30 seconds of audio in one synchronous call, for Inworld's TTS-2 models. The same operation is in the Inworld CLI and its bundled MCP server.

- Full: https://www.anchorterminal.com/tools/inworld-voice-cloning.md (~9,050 tokens) · this version ~2,080 tokens · JSON https://www.anchorterminal.com/tools/inworld-voice-cloning.json · canonical https://www.anchorterminal.com/tools/inworld-voice-cloning
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · MCP: https://www.anchorterminal.com/mcp · Updated: 2026-11-07 · pricing https://www.anchorterminal.com/tools/inworld-voice-cloning#pricing · reviews https://www.anchorterminal.com/tools/inworld-voice-cloning#reviews
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)

**C · 61.9/100 · rank #585 of 1486 · #4 in Voice cloning & custom voices · not agent-ready · confidence medium**


Assessment: One JSON call returns a usable voice ID from 3 to 30 seconds of audio, with no charge per clone and 100 custom voices on the free plan, behind keys that are read-only until write access is switched on. The API has no consent field, and Zero Data Retention excludes cloning samples.

## Facts

- Kind: Model API · vendor: Inworld AI · category: Voice cloning & custom voices · legal entity: Theai, Inc. dba Inworld AI · provenance 75/100
- Endpoint: `https://api.inworld.ai` (HTTP, stdio, Streamable HTTP)
- Auth: API key · pricing: Freemium · x402: no · licence: Proprietary service under Inworld's Terms of Service. The `@inworld/cli` and `@inworld/tts` npm packages and the examples repository are MIT
- Benchmark probes: not run yet, so Performance is pending
- Live, from our pollers (not part of the score): up at 2026-11-07 18:20 UTC · uptime 30 days 100.0% (200 probes) · p50 136 ms · p95 266 ms over 24 hours
- Surface listed: Inworld's Voice API cloning endpoints at https://api.inworld.ai, read from docs.inworld.ai, the pricing and terms pages on inworld.ai, the status page's GitHub issues and the published `@inworld/cli` 1.5.0 package on 6 November 2026. No account was created and no API call was made
- Sample length: 3 seconds minimum, 30 seconds used. The reference recommends 10 to 30 seconds. WAV or MP3 through the API, also webm in the Portal, 12 MB maximum
- Instant or professional: Instant is synchronous and generally available. Professional Voice Cloning is Beta, needs 10 minutes of audio and trains asynchronously
- Voice design: Yes, `POST /voices/v1/voices:design` from a text description, then `:publish`. Same rate limits as cloning
- Consent and verification: The Portal asks the user to confirm rights to clone the voice. The API request has no consent or verification field. No watermarking found in the docs
- Voice ownership: The docs say the creator stays owner of a voice shared to the Voice Library and grants Inworld a licence to host and distribute it. The Terms of Service (11 June 2025) have no clause specific to cloned voices or consent
- Endpoints: `POST /voices/v1/voices:clone`, `GET /voices/v1/voices`, `GET`, `PATCH` and `DELETE /voices/v1/voices/{voiceId}`, `GET /voices/v1/voices:customVoiceCapacity`, and copy tokens to move a voice between workspaces, on `https://api.inworld.ai`
- Models: Clones work on `inworld-tts-2` and `inworld-tts-2-flash`
- Rate limits: Voice cloning API requests a minute. On-Demand 2, Creator 3, Builder 5, Developer 10, Growth 20, Enterprise custom, per account across all keys
- Credentials: Workspace API key sent as HTTP Basic. Voice write access is an opt-in toggle per key. Deleting a key revokes it and every token minted from it
- Free tier: On-Demand plan is free with up to 70 minutes of TTS and 100 custom voices, and the docs say instant cloning is open to all users. Professional voice clones need a payment method on file
- Data retention: Cloning samples are kept to build and support the voice. Zero Data Retention does not cover them. No retention period published in the docs
- Regions: US by default. Isolated EU and India deployments for Enterprise, with voices and keys separate per region
- SDKs and tools: `@inworld/tts` 1.1.1 (npm, MIT, 6 May 2026), `inworld-tts` (PyPI), `@inworld/cli` 1.5.0 with the `inworld-mcp` server (npm, MIT, Node.js 20 or later)
- Custom voices: Cloned and designed voices share one limit per account. On-Demand 100, Creator 500, Builder 3,000, Developer 10,000, Growth 30,000, Enterprise custom, per the pricing page
- Prices: Speech from a clone, TTS-2, On-Demand $25 per 1M characters; Speech from a clone, TTS-2 Flash, On-Demand $15 per 1M characters; Creator plan $25 per month (plan); Builder plan $100 per month (plan); Developer plan $300 per month (plan); Growth plan $1500 per month (plan)

- Scores: Reliability 75, Performance pending, Schema & documentation 64, Agent ergonomics 64, Security & auth 55, Payments & pricing 40, Task success pending, Maintenance & community 68, Transparency & trust 63 · total over the 7 assessed categories
- Why: Reliability, Graded on the REST API, the surface an agent would call. · Schema & documentation, No OpenAPI file is linked from the docs or `llms.txt`, re-read on 6 November. · Agent ergonomics, The clone response echoes up to 15 seconds of processed audio as base64 with no way to leave it out. · Security & auth, Graded for voice cloning as the other listings in this category were, with consent and misuse controls in place of the read-only line and tr… · Payments & pricing, No x402, MPP or L402 (0). · Maintenance & community, Read as a model, on the lines inworld-tts and cartesia-voice-cloning use (recency 30, dated releases 10, deprecation notice 10, support 15… · Transparency & trust, Closed service with clear terms naming Theai, Inc.
- Sources: 15, open questions: 6, both in the full twin
- Capabilities: voice.clone, voice.design, speech.tts
- JSON: https://www.anchorterminal.com/api/v1/tools/inworld-voice-cloning.json
- Verify (for the vendor): the badge `https://www.anchorterminal.com/badges/inworld-voice-cloning.svg` or a link to https://www.anchorterminal.com/tools/inworld-voice-cloning from a page on inworld.ai or one of its subdomains, or the README at the root of github.com/inworld-ai/inworld-api-examples, then `POST https://www.anchorterminal.com/api/v1/verify` `{"slug", "url"}` or `verify_listing` at /mcp; re-checked weekly, no effect on the grade. Snippets in the full twin.
- Support: Discord https://discord.gg/inworld; support@inworld.ai; https://docs.inworld.ai/portal/support; https://docs.inworld.ai/; more in the full twin

## Before you call it

1. Create the key with write access (`inworld workspace add-key --write`). A default key gets code 7, insufficient access level, on `voices:clone`
2. Send the complete Base64 credential as `Authorization: Basic $INWORLD_API_KEY`. Don't encode it again
3. Send one 10 to 30 second WAV or MP3 clip as base64 in `voiceSamples[].audioData`. Audio past 30 seconds is cut
4. Don't blind-retry a clone. There's no idempotency key, so list voices with `filter=source="IVC"` first, and back off with jitter on 429
5. Set `gender`, `ageGroup` and `categories` with UpdateVoice afterwards. The clone call ignores them without an error
6. The response echoes up to 15 seconds of processed audio as base64 in `audioSamplesValidated`. Drop it before passing the result to a model

## Connect

```bash
npm install -g @inworld/cli
```

```bash
curl --location 'https://api.inworld.ai/voices/v1/voices:clone' \
  --header "Authorization: Basic $INWORLD_API_KEY" \
  --header 'Content-Type: application/json' \
  --data '{"displayName": "my_voice_clone_demo", "languageCode": "en-US", "voiceSamples": [{"audioData": "<base64-audio-data>"}]}'
```

```bash
claude mcp add inworld -- inworld mcp
```

## Similar tools

| Tool | Grade | Score | Shared capabilities | Slim |
| --- | --- | --- | --- | --- |
| ElevenLabs Voice Cloning and Voice Design API | BB | 76.8 | voice.clone, voice.design, speech.tts | https://www.anchorterminal.com/tools/elevenlabs-voice-cloning.min.md |
| Fish Audio Voice Cloning API | C | 61.5 | voice.clone, voice.design, speech.tts | https://www.anchorterminal.com/tools/fish-audio-voice-cloning.min.md |
| Gradium Voice Cloning and Voice Design | C | 60.8 | voice.clone, voice.design, speech.tts | https://www.anchorterminal.com/tools/gradium-voice-cloning.min.md |
| Ming-3.0-tts-0.5B | C | 59.3 | speech.tts, voice.clone, voice.design | https://www.anchorterminal.com/tools/ming-3-0-tts-0-5b.min.md |
| Inworld Realtime TTS-2 | C | 58.3 | speech.tts, voice.clone, voice.design | https://www.anchorterminal.com/tools/inworld-tts.min.md |


## Panel reviews (0, desk reviews from public material, no calls made)