Inworld Instant Voice Cloning vs Speechify API Voice Cloning

Inworld Instant Voice Cloning 64

The clone response echoes up to 15 seconds of processed audio as base64 with no way to leave it out. The MCP tool returns a compact result, but the server loads 40 tools with no toolsets, registering only those the credentials can call (13 of 25). Voice lists take an AIP-160 filter, pageSize, pageToken and orderBy, including source = "IVC", and a capacity endpoint reports used and maximum custom voices (20). Errors are a numeric code, a message and details, and the one example reads clearly, but no list is documented for the Voice API (12 of 20). No idempotency key, no MCP annotations in the 1.5.0 package, and the SDKs retry 5xx and network errors twice by default (4 of 20). Two required fields, language auto-detection, and official Python and Node.js SDKs (15). 13+20+12+4+15 = 64.

Speechify API Voice Cloning 97

Creating a voice returns a compact voice object, and GET /v1/voices takes type=personal to list only the workspace's clones (25). Voice lists page by cursor with limit up to 200 and the type filter (20). Machine-readable error codes with a fields map for validation failures, and the consent guide names three separate 422 codes and a 409 for an expired challenge (20). Idempotency-Key on voice creation, with idempotency_conflict on reuse (20). Cloning needs two calls and five fields because of the consent step, with official Python and TypeScript SDKs, both at 5.0.0 since 29 October (12 of 15).

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.

Speechify API Voice Cloning 87

Graded for voice cloning, 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, since the API returns audio and IDs rather than third-party text. Service-account keys with scopes (voices:read, voices:write, audio:all), rotation with a grace window, and minted child keys capped at 24 hours (30). Every clone needs a single-use consent challenge, the speaker reads the phrase, and the create call is refused unless the words and speaker match, plus output watermarking with a detection endpoint (20). The trust page says Speechify never trains on customer data. The Biometric Data Retention and Destruction Policy, effective 6 October 2026, destroys voice samples, voice models and verification data within 30 days of the voice's deletion, consent withdrawal or account closure, and at most 24 months after the last interaction, with backups gone within 90 days. Consent records without biometric data are kept 5 years, and no period is stated for TTS text and audio (14 of 15). Usage and spend roll up per service account, and GET /v1/projects/{project_id}/audit gives a 90-day trail of who changed a project's access and when, with no per-call log found (11 of 15). security.txt valid (its Expires date sat a year ahead on 6 October, 17 October and 1 November) pointing to a trust page that claims SOC 2 Type II, with the report on Enterprise per the pricing page; no bug bounty or public advisories found (12 of 20). 30 + 20 + 14 + 11 + 12 = 87.

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.

Speechify API Voice Cloning 94

OpenAPI 3.1 at docs.speechify.ai/openapi.json with 23 paths, including consent challenges, projects, webhooks and entitlements, re-read on 1 November. The WebSocket input stream added on 8 October isn't among the 23 paths (25). llms.txt per section, Markdown pages and a docs-search MCP server (10). The consent guide, re-read on 1 November, and the cloning overview explain the flow, when a request will be refused and how to branch on each refusal code (16 of 20). Inputs typed, with a gender enum, sample and consent recording length limits, though locale is a free string (13 of 15). Each endpoint lists its error codes and statuses, with examples (15). Dated Speechify-Version header and a changelog with entries several times a month (15). 25 + 10 + 16 + 13 + 15 + 15 = 94.

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.

Speechify API Voice Cloning 20

No x402, MPP or L402 (0). Per-unit overage prices are public, re-read on 1 November, $10, $8 and $6 per million characters by plan on Simba 3.0 and 3.2, and Simba 3.5 lists at $20, $16 and $12, billed at the lower rates until 21 November 2026 (20). The Free plan can't clone and has no voice design (0). Signup is a human browser flow (0).

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.

Speechify API Voice Cloning 90

Status page at status.speechify.ai (Better Stack) with an API component (20). The API shows 100 per cent uptime over the 90 days from 4 August to 1 November 2026 and the incident feed lists none. The Documentation component shows 35 minutes of downtime on 12 October and the Console component downtime on 23 days, every day from 4 to 22 August among them and under 25 minutes on each of 15 and 19 September and 16 and 19 October, neither of them the API (30). Rate and concurrency limits published per plan, 1 to 150 sustained requests a second and 3 to 100 concurrent, re-read on 1 November (15). 429 comes with Retry-After, rate_limited and concurrency_limit_reached codes, RateLimit headers and exponential backoff guidance, and POST /v1/voices takes an Idempotency-Key with a 24 hour replay window (15). No SLA found (0). Cloning is generally available (10). 20 + 30 + 15 + 15 + 0 + 10 = 90.

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.

Speechify API Voice Cloning 75

Closed service with clear API terms, SDKs under MIT (15 of 30). Terms (10 June 2024) and the trust page say customer data isn't used for training. The biometric data policy of 6 October 2026 sets destruction periods for voice samples, voice models and verification data, 5 years for consent records and 90 days for backups, and names service providers only by role. No public DPA (a custom DPA is listed on Enterprise), no subprocessor list and no period for TTS inputs and outputs were found (18 of 30, as for spider-cloud's stated periods with no public DPA). The September consent change was announced on 13 August, 41 days ahead, Simba 1.6 was retired at version 2026-09-21 with a dated switch on 2026-11-21 (simba-multilingual then served by Simba 3.5), the legacy api.sws.speechify.com host has a dated end of 19 January 2027 with Deprecation and Sunset headers, and legacy headers have a stated end date in mid-2027 (20). The regions guide of 17 October says accounts, keys, voices, usage and logs stay in the United States on every host and synthesis runs in US East or the Netherlands. No subprocessor list found (10 of 20, as for modal-sandboxes' region disclosure without a list). 15 + 18 + 20 + 10 = 63.