# Cartesia Voice Cloning API + MCP vs Inworld Instant Voice Cloning (slim)

> 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.

- Full: https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-inworld-voice-cloning.md (~5,800 tokens) · this version ~3,280 tokens · JSON https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-inworld-voice-cloning.json · canonical https://www.anchorterminal.com/compare/cartesia-voice-cloning-vs-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
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)

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: C 58.3, rank #755 of 1510 · https://www.anchorterminal.com/tools/cartesia-voice-cloning.min.md
- Inworld Instant Voice Cloning: C 61.9, rank #588 of 1510 · https://www.anchorterminal.com/tools/inworld-voice-cloning.min.md
- Cartesia Voice Cloning API + MCP, 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.
- Inworld Instant Voice Cloning, 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 Free to start without a card; No incidents deducted, where Cartesia Voice Cloning API + MCP loses 3 points for them.

| Category | Cartesia Voice Cloning API + MCP | Inworld Instant Voice Cloning |
| --- | --- | --- |
| Reliability (16%) | 73 | 75 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 85 | 64 |
| Agent ergonomics (13%) | 65 | 64 |
| Security & auth (14%) | 42 | 55 |
| Payments & pricing (10%) | 10 | 40 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 84 | 68 |
| Transparency & trust (7%) | 73 | 63 |

| Fact (where they differ) | Cartesia Voice Cloning API + MCP | Inworld Instant Voice Cloning |
| --- | --- | --- |
| 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 |
| Price for voice cloning | not published | $15 per 1M characters |
| 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 |
| 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 |
| 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 |

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.)