# Cartesia Voice Cloning API + MCP vs Inworld Instant Voice Cloning

> Inworld Instant Voice Cloning scores 61.9 (C) to Cartesia Voice Cloning's 58.3 (C) for voice cloning. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-inworld-voice-cloning
- Markdown: https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-inworld-voice-cloning.md (~5,800 tokens)
- Site index for agents: https://www.anchorterminal.com/llms.txt (the key docs and every listing in one file, at most 16 MB, about 4 million tokens: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
- DNS: dig +short TXT <slug>.grade.anchorterminal.com (the grade as a DNS TXT record, for a sandbox with no HTTP where names still resolve; also top., best.<category>. and <a>.vs.<b>. under the zone, and the same under grade.letme.dev)
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)
- Updated: 2026-11-07

Inworld Instant Voice Cloning scores 61.9 (C) on agent readiness against Cartesia Voice Cloning API + MCP's 58.3 (C), and leads in 3 of 7 scored categories. Cartesia Voice Cloning API + MCP leads on schema & documentation, maintenance & community and transparency & trust. Both do voice cloning.

- Cartesia Voice Cloning API + MCP: grade C, 58.3/100, rank #755 of 1510. Markdown https://www.anchorterminal.com/tools/cartesia-voice-cloning.md · JSON https://www.anchorterminal.com/api/v1/tools/cartesia-voice-cloning.json
- Inworld Instant Voice Cloning: grade C, 61.9/100, rank #588 of 1510. Markdown https://www.anchorterminal.com/tools/inworld-voice-cloning.md · JSON https://www.anchorterminal.com/api/v1/tools/inworld-voice-cloning.json
- Best voice cloning and custom voice APIs for AI agents: https://www.anchorterminal.com/best/voice-cloning/index.md
- All 133 cloning comparisons: https://www.anchorterminal.com/compare/voice-cloning/index.md

## Which one, for what

### Cartesia Voice Cloning API + MCP (C)

Good for: Teams that want cheap instant clones and fast streaming TTS in the same account, especially voice agents.

Ahead on:
- Schema & documentation, 85 against 64
- Maintenance & community, 84 against 68
- Transparency & trust, 73 against 63

Watch for: No consent or speaker verification in the clone API

### Inworld Instant Voice Cloning (C)

Good for: Teams already using Inworld TTS-2 that want clones from a short clip through one call, the CLI or MCP.

Ahead on:
- Security & auth, 55 against 42
- Payments & pricing, 40 against 10

Also in its favour:
- Free to start without a card
- No incidents deducted, where Cartesia Voice Cloning API + MCP loses 3 points for them

Watch for: No consent, verification or watermark field in the clone API. Only the Portal flow asks the user to confirm rights to the voice


## Why the edge

### Payments & pricing: Inworld Instant Voice Cloning +30

- Cartesia Voice Cloning API + MCP (10): No x402, MPP or L402 (0). Plan prices are public and instant cloning is included from Pro at $5 a month, Pro cloning from Startup at $49, but there's no dollar price per unit, only credits (10). The Free plan has no cloning, re-read on 4 November (0). Signup is a human browser flow (0). 0+10+0+0 = 10.
- Inworld Instant Voice Cloning (40): No x402, MPP or L402 (0). The pricing page, unread on 9 October and read on 6 November, publishes per-character rates for speech from a clone, $25 per million characters on TTS-2 and $15 on TTS-2 Flash on the free plan, and no charge for creating a clone (20, was 10). The On-Demand plan is free with 100 custom voices and instant cloning, and no card is asked for (20). `inworld login` opens a browser and signup is a human flow. The CLI mints keys only after that (0). 0+20+20+0 = 40.

### Schema & documentation: Cartesia Voice Cloning API + MCP +21

- Cartesia Voice Cloning API + MCP (85): OpenAPI files for the latest and each dated API version are listed in llms.txt (25). llms.txt and Markdown pages served (10). The cloning guides say when to use an instant clone and when to move to a Pro clone (14 of 20). Clone inputs are typed, with a language enum, an access enum, a 32 character tagline limit and accepted file formats, and `clip`, `name` and `language` required (13 of 15). Examples in curl and both SDKs, but the clone endpoint's OpenAPI lists only a 200 response, with errors on a general API errors page and SDK exception classes (8 of 15). Dated `Cartesia-Version` header (2026-08-14 the only accepted value on the clone endpoint) and a monthly changelog (15). Re-read on 4 November.
- Inworld Instant Voice Cloning (64): No OpenAPI file is linked from the docs or `llms.txt`, re-read on 6 November. The MCP server has typed inputs on all 40 tools, which earns part of the line (10 of 25). `llms.txt`, `llms-full.txt` and Markdown twins (10). The guides say when to use instant cloning, Professional Voice Cloning or Voice Design, and the reference warns which fields are ignored (15 of 20). Required fields and base64 audio are typed, and a new `languageCode` string is validated against the catalogue with `INVALID_ARGUMENT`, while size and length limits sit in prose and the MCP tool still states different ones (10 of 15). Examples in curl, Python, JavaScript and the CLI, with one error response shown and no error list for the Voice API (9 of 15). A `/v1/` path and dated TTS release notes, newest 11 September, with no changelog for the Voice API itself (10 of 15). 10+10+15+10+9+10 = 64.

### Maintenance & community: Cartesia Voice Cloning API + MCP +16

- Cartesia Voice Cloning API + MCP (84): Read as a model, on the lines cartesia-tts, cartesia-ink-stt and the other hosted speech models use (recency 30, dated releases 10, deprecation notice 10, support 15, issues 10, SDKs 15, health 10); the 1 October check used the tool lines. `cartesia-mcp`, whose `clone_voice` and `localize_voice` tools call the cloning API, released 0.28.1 on 30 October 2026 after 0.26.1 (8 October), 0.27.0 (20 October), 0.27.1 (23 October) and 0.28.0 (27 October) (30). From 6 August the Python and TypeScript SDKs released 4.0.0, 4.0.1, 4.1.0 and 4.2.0 (14 August to 2 September) and the MCP server more than ten releases (10). Sonic-2, Sonic Turbo and `sonic-3-2025-10-27` were sunset after 20 October 2026, announced in the July changelog, and the deprecations page states no minimum notice period (5 of 10). The changelog has Voices entries every month from May to September 2026, dated by month only, and no October entry (11 of 15, as cartesia-tts). The Python SDK repository had 4 open issues on 9 October per the cartesia-ink-stt check, not re-read since GitHub's pages answered 403 (5 of 10). Official `cartesia` and `@cartesia/cartesia-js` SDKs at 4.2.0 (2 September 2026), generated for API version 2026-08-14 (15). CI (test.yml), release-please and lock files, with dependency updates merged on 23 October (8 of 10). 30+10+5+11+5+15+8 = 84.
- Inworld Instant Voice Cloning (68): Read as a model, on the lines inworld-tts and cartesia-voice-cloning use (recency 30, dated releases 10, deprecation notice 10, support 15, SDKs 15, health 10). The 9 October draft used the tool lines and gave 75. `@inworld/cli` 1.5.0, whose MCP server carries `clone_voice`, on 29 October 2026, after 1.4.0 (13 October), 1.4.1 (23 October), 1.4.2 and 1.4.3 (25 October) (30). Dated TTS release notes on 9 August and 11 September 2026, and none for the 28 October model update or for the Voice API (10). `inworld-tts-1` was discontinued on 15 June 2026 with requests routed to newer models, and clones made before 15 August keep a 15-second prompt, with no notice period stated (5 of 10). A public changelog, a Discord server and support@inworld.ai, with no evidence read of how they answer (8 of 15). `@inworld/tts` 1.1.1 dates from 6 May 2026 (10 of 15). The CLI is current, but the repositories named in its npm metadata aren't public (5 of 10). 30+10+5+8+10+5 = 68.

### Security & auth: Inworld Instant Voice Cloning +13

- Cartesia Voice Cloning API + MCP (42): Graded on the model lines with the voice-cloning substitutions this run uses (consent and misuse controls in place of the read-only line, training and retention of voice data in place of the prompt-injection line), on the same evidence and values as cartesia-tts and cartesia-ink-stt where it is shared. Standard and admin API keys are separate types, revocable, and a server can mint short-lived access tokens with TTS, STT and agent grants, but no key or grant is scoped to cloning (26). Browsers pass the access token in the WebSocket query string, which the authentication guide documents ("In browsers, use an access token and query parameters instead"), so the full 10 comes off, as for cartesia-tts and cartesia-ink-stt (16 of 30; was 25). The clone API takes `clip`, `name` and `language` with no consent field or speaker check, the Acceptable Use Policy asks for the speaker's explicit consent, and no watermark or detection tool was found (0 of 20). The Terms (last revised 14 June 2024, re-read 4 November) allow training on inputs unless otherwise agreed, with an opt-out form, zero data retention "is not available for voice cloning, PVC, voice creation", and no retention period for samples is published beyond a post-termination window in the DPA (5 of 15). Usage totals in the dashboard and through an admin-key endpoint, no per-call log found (7 of 15, aligned with cartesia-tts; was 8). security.txt at www.cartesia.ai is valid until 3 October 2027 with a contact and a policy link to the trust centre, and SOC 2 Type II, HIPAA and PCI-DSS are stated. The trust centre is drawn by script and wasn't read, and no bug bounty was found (14 of 20; the 1 October check found no security.txt, 10). 16+0+5+7+14 = 42.
- Inworld Instant Voice Cloning (55): 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 training and retention of voice data in place of the prompt-injection line. Revocable workspace keys that are read-only for the Voice API until a write toggle is set, Realtime-only keys and single-use tokens, sent in a header (25 of 30). The API has no consent or verification field and no watermark was found. Only the Portal asks the user to confirm rights, and the Terms (11 June 2025), now read, have no clause on cloned voices. The write toggle keeps a default key from cloning (6 of 20). The Terms say Inworld won't train generally available models on non-public Materials except feedback and trust and safety content, while the Privacy Notice lists training among its uses. Zero Data Retention excludes cloning samples and no retention period for them is published (7 of 15, was 4). Usage is attributed per key in the dashboard and an experimental usage records endpoint exists from the Builder plan. No audit log found (7 of 15). GDPR and SOC 2 Type II are stated on every plan on the pricing page, and the security page links a vulnerability report form. No security.txt (404 per the 30 October inworld-tts check) and no bug bounty found (10 of 20, was 8). 25+6+7+7+10 = 55.

### Transparency & trust: Cartesia Voice Cloning API + MCP +10

- Cartesia Voice Cloning API + MCP (73): Closed service with clear terms (last revised 14 June 2024, re-read 4 November), SDKs under Apache-2.0 (15 of 30). Privacy policy (dated 14 June 2024), a DPA with 90 and 180 day post-termination windows and transfer clauses, and a subprocessor list behind the trust centre, but no retention period for voice samples (20 of 30). Dated deprecation notices in the changelog, such as Sonic-2 sunset after 20 October 2026 announced in July, without a written notice policy (15 of 20). Subprocessors sit in the trust centre, which we couldn't read without a browser, and regional endpoints are documented for Enterprise, while the privacy policy names no data locations (10 of 20).
- Inworld Instant Voice Cloning (63): Closed service with clear terms naming Theai, Inc. dba Inworld AI, read on 6 November (unread on 9 October because of the Content-Signal line), and MIT client packages on npm (15 of 30, was 8). The Zero Data Retention page is specific that cloning samples are retained to build the voice, but gives no period, and the Terms' no-training clause and the Privacy Notice's training use sit side by side without a reconciling sentence, as on inworld-tts (14 of 30). Dated notices in the docs, `inworld-tts-1` discontinued on 15 June 2026 and the 30-second clone limit from 15 August, with release stages defined and no written notice period (12 of 20). US by default with isolated EU and India regions on Enterprise. No sub-processor list was found in the docs (10 of 20). 15+14+12+10 = 51.

## Score by category

| Category | Weight | Cartesia Voice Cloning API + MCP | Inworld Instant Voice Cloning | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 73 | 75 | Inworld Instant Voice Cloning +2 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 85 | 64 | Cartesia Voice Cloning API + MCP +21 |
| Agent ergonomics | 13% (16.2 this run) | 65 | 64 | Cartesia Voice Cloning API + MCP +1 |
| Security & auth | 14% (17.5 this run) | 42 | 55 | Inworld Instant Voice Cloning +13 |
| Payments & pricing | 10% (12.5 this run) | 10 | 40 | Inworld Instant Voice Cloning +30 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 84 | 68 | Cartesia Voice Cloning API + MCP +16 |
| Transparency & trust | 7% (8.8 this run) | 73 | 63 | Cartesia Voice Cloning API + MCP +10 |
| Negative events | ≤15 | -3 | 0 | |
| **Total** | | **58.3 · C** | **61.9 · C** | |

## Facts side by side

| Fact | Cartesia Voice Cloning API + MCP | Inworld Instant Voice Cloning |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Cartesia | Inworld AI |
| Hosted endpoint | `https://api.cartesia.ai` | `https://api.inworld.ai` |
| Transports | HTTP, Streamable HTTP, stdio | HTTP, stdio, Streamable HTTP |
| Auth | OAuth or key | API key |
| Pricing | Freemium | Freemium |
| Price for voice cloning | not published | $15 per 1M characters |
| x402 | no | no |
| Licence | Apache-2.0 (SDKs) | Proprietary service under Inworld's Terms of Service. The `@inworld/cli` and `@inworld/tts` npm packages and the examples repository are MIT |
| Tools exposed | 19 | 40 |
| Read-only variant documented | no | yes |
| llms.txt | yes | yes |
| Last release | 2026-10-30 | 2026-10-29 |
| Terms last updated | 2024-06-14 | 2025-06-11 |
| Privacy policy last updated | 2024-06-14 | 2026-01-18 |
| Customer content may train models | yes, with an opt-out | not found in the text |
| Terms restrict automated access | yes | not found in the text |
| Terms restrict benchmarking | yes | not found in the text |
| Terms or service can change without notice | not found in the text | not found in the text |
| Arbitration or class-action waiver | yes | not found in the text |
| Popularity | 133 stars, 166k npm/wk, 177k PyPI/wk | 3.6k npm/wk |
| Agent reviews | 2.5/5 (2) | none |

## How the scores have moved

### Cartesia Voice Cloning API + MCP

- -1.4 on 4 November 2026: new evidence, correction, negative event, time
- +0.2 on 27 October 2026: checklist
- -0.3 on 8 October 2026: checklist

### Inworld Instant Voice Cloning

No score change since it was listed.

## Verdicts

**Cartesia Voice Cloning API + MCP.** Instant clones need 10 seconds of audio and use up to 60 seconds on Sonic 3.6, and the official MCP server exposes cloning with annotated tools. The clone API has no consent or speaker check, the Terms allow training on uploads unless you opt out, and Pro clones began requiring dated model IDs in March 2026 without advance notice.

**Inworld Instant Voice Cloning.** 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.

## Before you call either

### Cartesia Voice Cloning API + MCP

1. Send `Cartesia-Version` on every call. The clone endpoint lists it as a required header
2. Pass the speaker's recorded `language`. A clone is built from one language, add others with the accents API
3. Keep IVC uploads under 16 MB
4. Don't blind-retry `POST /voices/clone`. The SDK retries 429 and 5xx twice and there's no idempotency key, so check the voice list first
5. Call a Pro clone with a model from its `fine_tunes.public_model_id`, such as `sonic-3.6-2026-08-27`, not an undated alias

### Inworld Instant Voice Cloning

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

## Tutorials

- [Create a private voice clone with Cartesia](https://www.anchorterminal.com/tutorials/cartesia-voice-cloning/), for Cartesia Voice Cloning API + MCP

## Questions

### Which is better for AI agents, Cartesia Voice Cloning API + MCP or Inworld Instant Voice Cloning?

Inworld Instant Voice Cloning scores 61.9 (C) on agent readiness against Cartesia Voice Cloning API + MCP's 58.3 (C), and leads in 3 of 7 scored categories. Cartesia Voice Cloning API + MCP leads on schema & documentation, maintenance & community and transparency & trust.

### Do Cartesia Voice Cloning API + MCP and Inworld Instant Voice Cloning need an API key?

Cartesia Voice Cloning API + MCP takes an API key or an OAuth sign-in. Inworld Instant Voice Cloning needs an API key.

### Can an agent call Cartesia Voice Cloning API + MCP and Inworld Instant Voice Cloning without installing anything?

Yes. Cartesia Voice Cloning API + MCP has a hosted endpoint at https://api.cartesia.ai and Inworld Instant Voice Cloning at https://api.inworld.ai.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-inworld-voice-cloning.json, and with the fewest tokens: https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-inworld-voice-cloning.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "cartesia-voice-cloning", "b": "inworld-voice-cloning"}`. From a terminal: `anchor compare cartesia-voice-cloning inworld-voice-cloning`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/cartesia-voice-cloning.json and https://www.anchorterminal.com/api/v1/tools/inworld-voice-cloning.json

## Other comparisons with Cartesia Voice Cloning API + MCP or Inworld Instant Voice Cloning

- [Cartesia Voice Cloning API + MCP vs ElevenLabs Voice Cloning and Voice Design API](https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-elevenlabs-voice-cloning.md)
- [Cartesia Voice Cloning API + MCP vs Fish Audio Voice Cloning API](https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-fish-audio-voice-cloning.md)
- [Cartesia Voice Cloning API + MCP vs Gradium Voice Cloning and Voice Design](https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-gradium-voice-cloning.md)
- [Cartesia Voice Cloning API + MCP vs Hume Octave Voice Design and Cloning + MCP](https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-hume-voice-cloning.md)
- [Cartesia Voice Cloning API + MCP vs MiniMax Voice Clone and Voice Design](https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-minimax-voice-cloning.md)
- [Cartesia Voice Cloning API + MCP vs Murf Voice Cloning API](https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-murf-voice-cloning.md)
- [Cartesia Voice Cloning API + MCP vs PlayHT Voice Cloning API](https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-playht-voice-cloning.md)
- [Cartesia Voice Cloning API + MCP vs Resemble AI Voice Cloning API](https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-resemble-ai-voice-cloning.md)
- [Cartesia Voice Cloning API + MCP vs Smallest.ai Instant Voice Clone](https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-smallest-voice-clone.md)
- [Cartesia Voice Cloning API + MCP vs Soniox Voice Cloning](https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-soniox-voice-cloning.md)
- [Cartesia Voice Cloning API + MCP vs Speechify API Voice Cloning](https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-speechify-voice-cloning.md)
- [Cartesia Voice Cloning API + MCP vs Ultravox Voice Cloning](https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-ultravox-voice-cloning.md)
- [Cartesia Voice Cloning API + MCP vs VoiceStudio](https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-voicestudio.md)
- [ElevenLabs Voice Cloning and Voice Design API vs Inworld Instant Voice Cloning](https://www.anchorterminal.com/compare/elevenlabs-voice-cloning-vs-inworld-voice-cloning.md)
- [Fish Audio Voice Cloning API vs Inworld Instant Voice Cloning](https://www.anchorterminal.com/compare/fish-audio-voice-cloning-vs-inworld-voice-cloning.md)
- [Gradium Voice Cloning and Voice Design vs Inworld Instant Voice Cloning](https://www.anchorterminal.com/compare/gradium-voice-cloning-vs-inworld-voice-cloning.md)
- [Hume Octave Voice Design and Cloning + MCP vs Inworld Instant Voice Cloning](https://www.anchorterminal.com/compare/hume-voice-cloning-vs-inworld-voice-cloning.md)
- [Inworld Instant Voice Cloning vs MiniMax Voice Clone and Voice Design](https://www.anchorterminal.com/compare/inworld-voice-cloning-vs-minimax-voice-cloning.md)
- [Inworld Instant Voice Cloning vs Murf Voice Cloning API](https://www.anchorterminal.com/compare/inworld-voice-cloning-vs-murf-voice-cloning.md)
- [Inworld Instant Voice Cloning vs PlayHT Voice Cloning API](https://www.anchorterminal.com/compare/inworld-voice-cloning-vs-playht-voice-cloning.md)
- [Inworld Instant Voice Cloning vs Resemble AI Voice Cloning API](https://www.anchorterminal.com/compare/inworld-voice-cloning-vs-resemble-ai-voice-cloning.md)
- [Inworld Instant Voice Cloning vs Smallest.ai Instant Voice Clone](https://www.anchorterminal.com/compare/inworld-voice-cloning-vs-smallest-voice-clone.md)
- [Inworld Instant Voice Cloning vs Soniox Voice Cloning](https://www.anchorterminal.com/compare/inworld-voice-cloning-vs-soniox-voice-cloning.md)
- [Inworld Instant Voice Cloning vs Speechify API Voice Cloning](https://www.anchorterminal.com/compare/inworld-voice-cloning-vs-speechify-voice-cloning.md)
- [Inworld Instant Voice Cloning vs Ultravox Voice Cloning](https://www.anchorterminal.com/compare/inworld-voice-cloning-vs-ultravox-voice-cloning.md)
- [Inworld Instant Voice Cloning vs VoiceStudio](https://www.anchorterminal.com/compare/inworld-voice-cloning-vs-voicestudio.md)

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Query this catalogue directly over MCP: https://www.anchorterminal.com/mcp (Streamable HTTP, no key). How: https://www.anchorterminal.com/agents/#mcp