# Gradium Voice Cloning and Voice Design vs Inworld Instant Voice Cloning (slim)

> Inworld Instant Voice Cloning scores 61.9 (C) to Gradium Voice Cloning and Voice Design's 60.8 (C) for voice cloning. Prices, MCP, x402, uptime and agent notes side by side.

- Full: https://www.anchorterminal.com/compare/gradium-voice-cloning-vs-inworld-voice-cloning.md (~5,000 tokens) · this version ~2,580 tokens · JSON https://www.anchorterminal.com/compare/gradium-voice-cloning-vs-inworld-voice-cloning.json · canonical https://www.anchorterminal.com/compare/gradium-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 Gradium Voice Cloning and Voice Design's 60.8 (C), and leads in 3 of 7 scored categories. Gradium Voice Cloning and Voice Design leads on schema & documentation. Both do voice cloning.

- Gradium Voice Cloning and Voice Design: C 60.8, rank #637 of 1486 · https://www.anchorterminal.com/tools/gradium-voice-cloning.min.md
- Inworld Instant Voice Cloning: C 61.9, rank #585 of 1486 · https://www.anchorterminal.com/tools/inworld-voice-cloning.min.md
- Gradium Voice Cloning and Voice Design, good for Builders on Gradium's TTS who want instant clones and designed voices in five European languages with EU residency. Ahead on Schema & documentation, 83 against 64.
- 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 Reliability, 75 against 63; Security & auth, 55 against 48; Payments & pricing, 40 against 30. Also Runs on your own machine.

| Category | Gradium Voice Cloning and Voice Design | Inworld Instant Voice Cloning |
| --- | --- | --- |
| Reliability (16%) | 63 | 75 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 83 | 64 |
| Agent ergonomics (13%) | 67 | 64 |
| Security & auth (14%) | 48 | 55 |
| Payments & pricing (10%) | 30 | 40 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 70 | 68 |
| Transparency & trust (7%) | 63 | 63 |

| Fact (where they differ) | Gradium Voice Cloning and Voice Design | Inworld Instant Voice Cloning |
| --- | --- | --- |
| Vendor | Gradium SAS | Inworld AI |
| Hosted endpoint | `https://api.gradium.ai/api/voices/` | `https://api.inworld.ai` |
| Transports | HTTP, websocket | HTTP, stdio, Streamable HTTP |
| Price for voice cloning | not published | $15 per 1M characters |
| Licence | Proprietary service under Gradium's Terms of Service (version of 19 October 2026). The `gradium` Python SDK is on PyPI | Proprietary service under Inworld's Terms of Service. The `@inworld/cli` and `@inworld/tts` npm packages and the examples repository are MIT |
| Tools exposed | none | 40 |
| Read-only variant documented | no | yes |
| Last release | 2026-11-06 | 2026-10-29 |
| Terms last updated | no date given | 2025-06-11 |
| Privacy policy last updated | no date given | 2026-01-18 |
| Customer content may train models | yes | not found in the text |
| Popularity | none | 3.6k npm/wk |

Why the edge:
- Schema & documentation, Gradium Voice Cloning and Voice Design +19: Gradium Voice Cloning and Voice Design 83 (Public OpenAPI 3.1 file at docs.gradium.ai/api-reference/openapi.json (25). llms.txt and Markdown pages (10). The guides say when to clone, design, enhance or localise a voice, and the custom-voice page explains the enhancement default and how to opt out (14 of 20). The clone body has `audio_file`, `name` and `language` required, a five-value language enum and typed defaults for `start_s`, `enhance` and `timeout_s` (14 of 15). curl and Python examples. The create call documents only 201 and 422, and the errors page covers synthesis, with plain-text 500 bodies (9 of 15). Routes carry no version, the OpenAPI file is 0.1.0, and release notes are dated per entry, newest 6 November 2026 (11 of 15). The API reference FAQ gives a 300-second session where the limits page says 3,000. 25+10+14+14+9+11 = 83.); 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.)
- Reliability, Inworld Instant Voice Cloning +12: Gradium Voice Cloning and Voice Design 63 (Graded on the hosted voice API with the hosted lines. Atlassian Statuspage at gradium.statuspage.io with five components, one of them Voice Cloning (20). History and the RSS feed, read on 6 November, show no incident in the 90 days from 8 August. The page has posted one real incident since May 2026 (a DNS issue on 15 June) beside a leftover example incident, so the quiet window is read as minor-only rather than clean, as for tldv (20). Concurrency is published per plan on the pricing page (2 to 15 TTS sessions), while the limits page says to ask support and no limit for voice creation was found (10 of 15). No 429, Retry-After or backoff guidance was found; the errors page says to open a new connection after an error, and voice creation takes a `timeout_s` (3 of 15). No SLA in the Terms or on the pricing page (0). Instant cloning carries no beta label (10). 20+20+10+3+0+10 = 63.); Inworld Instant Voice Cloning 75 (Graded on the REST API, the surface an agent would call. Status page at status.inworld.ai, drawn from GitHub issues, with five components and none for cloning (20). Read through the GitHub API on 6 November, the 90 days from 8 August hold two incidents, 29 minutes of elevated TTS latency on 25 August and 26 minutes of elevated TTS 2.1 errors from a network fault at one GPU site on 28 October, both minor (20). Cloning limits are published per plan, 2 to 20 requests a minute (15). A 429 is documented with exponential backoff and jitter code, and since the 9 October check the rate-limits page says limits over a minute can carry `Retry-After`. No idempotency key or safe-retry guidance for clone creation (10 of 15, was 9). The pricing page, now read, names an SLA on Enterprise only with no terms or figure, as on inworld-tts (0). Instant cloning carries no Preview or Beta mark (10). 20+20+15+10+0+10 = 75.)
- Payments & pricing, Inworld Instant Voice Cloning +10: Gradium Voice Cloning and Voice Design 30 (No x402, MPP or L402 (0). Plan prices and credits are public, 1 credit a character for speech, with no dollar price per unit, as cartesia-voice-cloning is read. Creating a clone uses no credits in the docs (10). The free plan has 45,000 credits a month, 5 custom voices and Voice Design, and the site says no credit card is required. Commercial use starts on the $12 plan (20). Signup is a browser flow in Gradium Studio (0). 0+10+20+0 = 30.); 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.)
- Security & auth, Inworld Instant Voice Cloning +7: Gradium Voice Cloning and Voice Design 48 (Graded for voice cloning as the other listings in this category, 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. API keys per organisation in a header, revocable and able to expire, with no scopes found (20 of 30). No consent or verification field and no watermark. The Terms make the client obtain the consent of anyone whose voice is a sample and bar impersonation without explicit authorisation, and the API FAQ says explicit consent is required (6 of 20). The Terms grant Gradium a licence to use Client Data to improve its services and train its models, with no opt-out found, and zero data retention (paid plans) excludes voice samples, so samples are kept and may be used for training (2 of 15). Organisation roles and a member list, with no per-call audit log found (5 of 15). SOC 2 Type II and ISO 27001:2022 audited by A-LIGN, a trust centre and security@gradium.ai. No security.txt (404) and no bug bounty found (15 of 20). 20+6+2+5+15 = 48.); 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.)