# Inworld Realtime TTS-2 > Inworld's hosted text-to-speech models, inworld-tts-2 and inworld-tts-2-flash, over REST, HTTP streaming, WebSocket, async jobs and an OpenAI-compatible endpoint. TTS-2 takes bracketed steering, and an opt-in Reasoning step writes the delivery direction itself. - Canonical: https://www.anchorterminal.com/tools/inworld-tts - Pricing: https://www.anchorterminal.com/tools/inworld-tts#pricing - Reviews: https://www.anchorterminal.com/tools/inworld-tts#reviews - Markdown: https://www.anchorterminal.com/tools/inworld-tts.md (~9,250 tokens) - Slim: https://www.anchorterminal.com/tools/inworld-tts.min.md (~2,280 tokens, same facts, less prose, for token-sensitive contexts) - JSON: https://www.anchorterminal.com/tools/inworld-tts.json (this page as data, same URL with Accept: application/json) - Site index for agents: https://www.anchorterminal.com/llms.txt (full text: 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) - Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data) - Updated: 2026-10-31 ## Overview **Grade C · 58.3/100 · rank #687 of 1243 · #10 in Text-to-speech · not agent-ready · confidence medium** ## Assessment TTS-2 takes bracketed steering, and opt-in Reasoning writes a delivery direction from the text and up to 600 characters of context, returning it in the response. Per-character prices are public and the free plan needs no card. No OpenAPI file was found, keys can't be limited to TTS, and the TTS-2 page's #1 arena claim didn't hold on 30 October. ## Facts | Field | Value | | --- | --- | | Vendor | Inworld AI (https://inworld.ai) | | Kind | Model API | | Category | Text-to-speech (https://www.anchorterminal.com/categories/text-to-speech) | | Transport | HTTP, websocket | | Endpoint | `https://api.inworld.ai` | | Auth | API key · Every call sends `Authorization: Basic` with the Base64 `key_id:secret` credential copied from the Portal or printed by the CLI. Keys belong to a workspace, are deleted to revoke, and have write toggles only for the Voice and Router APIs, so no key is limited to TTS. Browser and mobile clients use single-use tokens minted server-side, valid 15 minutes by default. | | Pricing | Freemium ($25 / mo) · TTS-2 costs $25 per million characters on the free On-Demand plan, falling to $20, $17.50, $15 and $12.50 on the $25, $100, $300 and $1,500 monthly plans, and from $5 on Enterprise. TTS-2 Flash runs $15 down to $7. On-Demand includes up to 70 minutes of TTS with no card. Steering tags count as characters, while `synthesisContext` and `reasoningContext` aren't billed. Batch costs 20 per cent less (checked 2026-10-30). | | x402 | No · No x402, MPP or L402 in llms.txt, the TTS docs, the billing page or the pricing page (checked 2026-10-30). Usage is drawn from prepaid plan credits, card top-ups of at least $10 or auto-reload. | | Licence | Proprietary service under Inworld's Terms of Service. The Node.js SDK `@inworld/tts` and the CLI `@inworld/cli` are MIT on npm | | Packages | npm: `@inworld/tts`; pypi: `inworld-tts`; npm: `@inworld/cli` | | Docs | https://docs.inworld.ai/tts/tts | | llms.txt | https://docs.inworld.ai/llms.txt | | Last release | 2026-10-28 | | npm downloads / week | 3,632 | | Surface listed | Inworld's TTS API at https://api.inworld.ai with the `inworld-tts-2` and `inworld-tts-2-flash` models, read from docs.inworld.ai, the launch posts and the pricing, legal and security pages on 30 October 2026. No account was created and no API call was made | | Models | `inworld-tts-2` (steering, Reasoning, professional voice clones, 100 ms P90 server-side time to first byte per Inworld) and `inworld-tts-2-flash` (no steering, 20 ms per Inworld). `inworld-tts-1.5-max` and `-mini` are deprecated, and `inworld-tts-1` and `-1-max` were discontinued on 15 June 2026 with requests routed to newer models | | Endpoints | `POST /tts/v1/voice` (up to 2,000 UTF-16 units, base64 audio in JSON, 16 MB output cap), `POST /tts/v1/voice:stream` (up to 4,000, NDJSON), WebSocket `/v1/tts/synthesize:websocket`, `POST /tts/v1/voice:synthesizeAsync` (up to 100,000 characters, Preview), `voice:synthesizeBatch` (Preview) and OpenAI-compatible `POST /v1/audio/speech` | | Reasoning | `synthesisContext.reasoning` (`REASONING_ON`), optional `reasoningContext` up to 600 characters, never spoken and not billed, and `previousRequests` for earlier lines. The response carries `reasoningInstruction`, on the first message when streaming. An inline tag overrides it from where it appears. If no instruction is ready in time the text is synthesised without one, and synchronous requests start slightly later with it on. Launched 28 October 2026 | | Controls | Inline bracketed steering and non-verbals, `[reset]`, `deliveryMode` (STABLE, BALANCED, CREATIVE) on TTS-2, SSML break tags, inline IPA, named pronunciation dictionaries, language tags, verbatim tags, text normalisation on or off, and word or character timestamps with visemes | | Output | MP3 (default), LINEAR16, PCM, WAV, OGG_OPUS, FLAC, MULAW and ALAW, 8 to 48 kHz | | Languages | 623 language and locale codes covering 470 languages in three tiers. Tier 1 is 15 languages, Tier 2 is 79 and Tier 3 is 376 best-effort languages that Inworld hasn't evaluated | | Limits | Concurrent generations 5 on On-Demand, 10 Creator, 50 Builder, 150 Developer, 500 Growth. WebSocket connections 50 to 5,000. Voice cloning and design 2 to 20 requests a minute. Limits are per account and shared across keys | | Errors | gRPC-style JSON with `code`, `message` and `details`. The reference shows one 4XX example (code 5, unknown voice), and the concurrency page documents code 8 ResourceExhausted. 429 is documented with exponential backoff and jitter guidance. No full TTS error list was found | | Credentials | Workspace API keys in `Authorization: Basic`, deleted to revoke, with optional write toggles for the Voice and Router APIs and a separate Realtime-only key type. One-time tokens (single use, 15 minutes by default) for clients. Session tokens are deprecated | | Plans | On-Demand free, Creator $25, Builder $100, Developer $300 and Growth $1,500 a month, each with credits equal to the price that roll over for 3 months, and Enterprise custom with an SLA, DPA and EU or India residency | | Data handling | Zero data retention covers TTS text and audio on Enterprise, or as a Growth add-on. Usage metadata, voice cloning samples and voice design prompts are kept even then. Async and batch results stay in Inworld storage for about 7 days unless delivered to the customer's bucket | | Certifications | SOC 2 Type II, HIPAA and GDPR claimed on the security page, with details on a trust centre at trust.inworld.ai that wasn't read | | Other Inworld products | The same key and docs cover STT, the Realtime speech-to-speech API, voice cloning and design, and Inworld Inference for LLMs. The ultravox listing records Inworld's announcement of 30 September 2026 that it acquired Ultravox | | Independent ranking | On the Artificial Analysis provider-voice leaderboard, read 30 October 2026, Realtime TTS-2 was 8th (Elo 1,267, 2,527 appearances) and Realtime TTS-2 Flash 16th (Elo 1,217). Eleven v4 Turbo led at 1,336 | | Capabilities | speech.tts, speech.streaming, speech.voices, speech.ssml, speech.languages, speech.batch, voice.clone, voice.design | | Tags | hosted, official, closed-source, freemium, free-tier, no-card, llms-txt, streaming, openai-compatible, reasoning, multilingual, async-jobs, batch, typescript, python, cli, mcp, status-page, soc2, enterprise | | JSON | https://www.anchorterminal.com/api/v1/tools/inworld-tts.json | ## Score breakdown (methodology v0.7, October 2026 research run) Assessed 2026-10-30 from public evidence against the published checklist (https://www.anchorterminal.com/benchmark/#checklist). Confidence: medium. Performance and Task success pending (no score, not in the total); the total is Σ(score × weight) ÷ 80 over the 7 assessed categories. "This run" is each category's share of the 100 points. | Category | Weight | This run | Score (0–100) | Points | | --- | --- | --- | --- | --- | | Reliability | 16% | 20 | 62 | 12.4 | | Performance | 10% | pending | pending | n/a | | Schema & documentation | 13% | 16.2 | 60 | 9.8 | | Agent ergonomics | 13% | 16.2 | 68 | 11.1 | | Security & auth | 14% | 17.5 | 61 | 10.7 | | Payments & pricing | 10% | 12.5 | 40 | 5.0 | | Task success | 10% | pending | pending | n/a | | Maintenance & community | 7% | 8.8 | 68 | 6.0 | | Transparency & trust (editorial 51, provenance 75) | 7% | 8.8 | 63 | 5.5 | | Negative events | up to −15 | up to −15 | 30 October 2026. Inworld's Realtime TTS-2 page shows Realtime TTS-2 as #1 for voice quality on the Artificial Analysis Speech Arena and says the ranks come from the live arena, not hardcoded. Artificial Analysis's provider-voice leaderboard on the same day put Realtime TTS-2 8th (Elo 1,267) behind Eleven v4 Turbo (1,336). The page also says the table was verified in May 2026. The deduction lapses if the page is corrected or the rank returns. Sources: https://inworld.ai/blog/realtime-tts-2 and https://artificialanalysis.ai/text-to-speech/leaderboard/provider-voice (-2) | -2 | | **Total** | | | | **58.3 → C** | ### Why each score - Reliability 62 (checked 2026-10-30): Hosted reading of the checklist, on the TTS API. status.inworld.ai is a public status page running the issue-status app, which draws components and incidents from GitHub issues (20). Its history wasn't read, because GitHub's robots.txt couldn't be read from our environment, so no readable history (5). Concurrent generations, WebSocket connections and cloning and design requests a minute are published per plan, from 5 concurrent generations on the free plan to 500 on Growth (15). A 429 is documented with exponential backoff and jitter code, and the concurrency error (code 8) says which messages may have been dropped, but no Retry-After header is documented (12 of 15). An SLA is named on the Enterprise plan only, with no terms or uptime figure published (0). TTS-2 reached general availability on 31 August 2026 and Reasoning carries no Preview mark. Async and batch jobs are Preview (10). Total 62. - Performance: Pending. Latency is measured per call by our probes, which haven't run yet, so this run doesn't score it. Its weight is shared across the assessed categories until the first probe window closes. - Schema & documentation 60 (checked 2026-10-30): No OpenAPI or other machine-readable file was found. llms.txt and the API reference don't link one and the usual paths redirect to pages (0). llms.txt, llms-full.txt, a Markdown twin of every page and a keyless docs MCP server (10). The models page says which model suits what, the Reasoning guide says where it runs and where it doesn't yet (WebSocket, Realtime, batch), and the reference marks fields each model ignores (17 of 20). Typed fields with enums for encoding, `deliveryMode`, `reasoning` and `timestampType`, a sample-rate range, per-endpoint text limits and a 600-character cap on `reasoningContext` (14 of 15). Examples in curl, Python, JavaScript and the CLI, with one 4XX example and the concurrency error, and no TTS error list (9 of 15). Versioned `/v1` paths and dated TTS release notes, but the notes have no entry for the 28 October Reasoning launch and model update, and models have no dated snapshots (10 of 15). Total 60. - Agent ergonomics 68 (checked 2026-10-30): API reading of the checklist. Eight audio encodings from 8 to 48 kHz, timestamps only when asked, and synchronous, NDJSON streaming, WebSocket and async delivery. Reasoning adds one short string, `reasoningInstruction`, to the response (22 of 25). Text is capped at 2,000 or 4,000 UTF-16 units per request, and voices can be filtered by tags, but voice-list paging wasn't confirmed today (12 of 20). Errors carry a numeric gRPC-style code, a message and details, with one worked example and the code 8 behaviour explained, and no list (12 of 20). Synthesis is stateless and retry guidance is published, but the billing page says text is counted once synthesis starts, with no idempotency key (10 of 20). Three required fields, official Node.js and Python SDKs, the CLI, and an OpenAI-compatible endpoint that works with OpenAI's SDKs. The docs warn that SDK defaults may name older models (12 of 15). Total 68. - Security & auth 61 (checked 2026-10-30): Model reading of the checklist, with training and retention in place of the least-privilege and injection lines. Workspace API keys, deleted to revoke, with separate keys per environment advised, single-use client tokens valid 15 minutes, and a Realtime-only key type. No key can be limited to TTS, because write toggles cover only the Voice and Router APIs (25 of 30). The Terms (11 June 2025) say Inworld won't train generally available models on customers' non-public Materials, except feedback and content flagged for trust and safety. The Privacy Notice (18 January 2026) lists training AI models among its uses and covers voice data, while excluding data processed for enterprise customers (12 of 20). Zero data retention is Enterprise only or a Growth add-on. No retention period is published for other plans, async results are kept about 7 days, and whether the Reasoning model's step is covered isn't stated (6 of 15). Usage is attributed per key, and a Performance page (Builder and above) shows errors, latency and throttling. The Logs page sits behind the Portal login and wasn't read (8 of 15). SOC 2 Type II, HIPAA and GDPR claimed on the security page, with the trust centre unread. A vulnerability report form exists. No security.txt (404) and no bug bounty found (10 of 20). Total 61. - Payments & pricing 40 (checked 2026-10-30): No x402, MPP or L402 (0). Per-character prices for both models and every plan are on the public pricing page, $25 per million characters for TTS-2 on the free plan (20). The On-Demand plan is free with up to 70 minutes of TTS, and the pricing table lists no payment method for it (20). `inworld login` opens a browser sign-in and the CLI mints keys only after it, so a person signs up (0). Total 40. - Task success: Pending. Task success needs the category task suites run through each tool, which haven't run yet, so this run doesn't score it. Its weight is shared across the assessed categories until then. A data provider's data-quality score is published on its listing now and becomes half of this category when it's scored. - Maintenance & community 68 (checked 2026-10-30): Read as a model. Reasoning and an updated `inworld-tts-2` on 28 October 2026, and `@inworld/cli` 1.5.0 on 29 October (30). Dated TTS changes on 6 August, 9 August, 11 September and 28 October 2026 (10). `inworld-tts-1` and `-1-max` were discontinued on 15 June 2026 with requests routed to newer models, and the 1.5 models are deprecated with no end date, but no notice period was found (5 of 10). Public release notes, 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, before TTS-2 Flash and Reasoning, and the PyPI page answered with a bot check (10 of 15). The CLI is current, but the SDK and CLI repositories weren't read (5 of 10). Total 68. - Transparency & trust 63 (checked 2026-10-30): Closed service with clear terms naming Theai, Inc. dba Inworld AI, and MIT client packages on npm (15). The zero data retention page is specific about what is kept, but the Terms' no-training clause and the Privacy Notice's training use sit side by side without a reconciling sentence, and the privacy retention section gives no periods apart from up to three years for voice-derived biometric data (14 of 30). Dated discontinuation of `inworld-tts-1` with automatic rerouting and release-stage definitions, but no written notice policy, and the 28 October update replaced `inworld-tts-2` in place (12 of 20). US headquarters with isolated EU and India regions on Enterprise. No sub-processor list was found in the docs, and the trust centre wasn't read (10 of 20). Total 51. Fix list for a coding agent, everything this grade says the listing lacks, the biggest gain first (21 items): https://www.anchorterminal.com/fixes/inworld-tts.md (JSON https://www.anchorterminal.com/fixes/inworld-tts.json) ### What we couldn't check - Content-Signal. inworld.ai's robots.txt allows Claude agents on every path we read but carries `Content-Signal: ai-train=no, search=yes, ai-input=no`. The held inworld-instant-voice-cloning listing of 9 October was stopped on this signal pending the founder's decision, which we didn't find recorded. This run read eight inworld.ai pages (two launch posts, pricing, terms, privacy, security, the PlayHT guide and the sitemap) under this batch's robots.txt rule. If the stricter reading applies, those facts need another source or the listing is held. - unchecked: the status page's incident history, because it is drawn from GitHub issues and GitHub's robots.txt couldn't be read from our environment. The held 9 October dossier recorded two minor incidents in the 90 days before it. - unchecked: the PyPI page for `inworld-tts`, which answered with a bot check, and the SDK and CLI repositories on GitHub. - unchecked: the trust centre at trust.inworld.ai, for the SOC 2 report and any sub-processor list, and the Portal's Logs page, which needs a login. - Whether the generated `reasoningInstruction` is billed as characters, and whether zero data retention covers the language model that writes it. The docs say context fields aren't billed and are silent on both. - Inworld's claim that TTS-2 with Reasoning is the first speech model to decide how to say a line before saying it wasn't checked against other vendors and is recorded as Inworld's claim. - The 28 October post cites Cekura's benchmark (Flash 46 ms median first audio, fastest of 27, and TTS-2 93.4 per cent of hard items read correctly). The post dates Cekura's results 28 October in the text and 19 October under the chart. Cekura's page wasn't read, so these are Inworld's report of a third party. - domainRegistered is null because the RDAP lookup for inworld.ai failed. ### Sources - Reasoning and model update launch post, 28 October 2026: (seen 2026-10-30) - Realtime TTS-2 page with the arena comparison table: (seen 2026-10-30) - TTS release notes: (seen 2026-10-30) - Steering guide with the Reasoning section: (seen 2026-10-30) - Synthesise speech API reference: (seen 2026-10-30) - HTTP streaming synthesis: (seen 2026-10-30) - TTS models: (seen 2026-10-30) - llms.txt: (seen 2026-10-30) - billing, character counting and limits by plan: (seen 2026-10-30) - pricing: (seen 2026-10-30) - rate limits and 429 handling: (seen 2026-10-30) - concurrency limits and error code 8: (seen 2026-10-30) - API keys: (seen 2026-10-30) - security best practices and one-time tokens: (seen 2026-10-30) - zero data retention: (seen 2026-10-30) - support and release stages: (seen 2026-10-30) - Performance page: (seen 2026-10-30) - Inworld CLI and MCP server: (seen 2026-10-30) - Terms of Service: (seen 2026-10-30) - Privacy Notice: (seen 2026-10-30) - security page: (seen 2026-10-30) - status page (app shell only): (seen 2026-10-30) - Artificial Analysis provider-voice leaderboard: (seen 2026-10-30) - npm, @inworld/tts: (seen 2026-10-30) - npm, @inworld/cli: (seen 2026-10-30) - PlayHT migration guide: (seen 2026-10-30) ## Score history Every move of a score since the listing was graded, newest first, with its cause. A score can't move without an entry here. JSON: https://www.anchorterminal.com/api/v1/tools/inworld-tts/history.json - 2026-10-30: graded 58.3 C (methodology 0.7) ## Who's behind it (provenance 75/100, checked 2026-10-30) | Check | Finding | Points | | --- | --- | --- | | Legal entity named | Theai, Inc. dba Inworld AI | 20/20 | | Domain age | inworld.ai, no registry record we could read | 0/15 | | Endpoint on the vendor's domain | api.inworld.ai | 15/15 | | Terms of service | read, states 6 of the 7 things a reader expects | 9.1/10 | | Privacy policy | read, states 7 of the 8 things a reader expects | 9.3/10 | | Status page | status.inworld.ai | 10/10 | | Changelog | published | 10/10 | | security.txt | not found | 0/10 | | People named | 3 named with their role, none with a public profile | 7/10 | | Support route | a support address, help pages, a community | 5/5 | The Terms of Service (effective 11 June 2025) are an agreement with Theai, Inc. dba Inworld AI under California law, with courts in Santa Clara. The Privacy Notice (last updated 18 January 2026) names Theai, Inc. inworld.ai/.well-known/security.txt returns 404. The security page links a vulnerability report form. status.inworld.ai runs the open-source issue-status app, which draws incidents from GitHub issues in inworld-ai/inworld-issue-status. Its history wasn't read, because GitHub's robots.txt couldn't be read from our environment. inworld.ai's robots.txt allows Claude agents on the paths read and sets `Content-Signal: ai-train=no, search=yes, ai-input=no`. docs.inworld.ai has no such signal. The domain's registration date wasn't established, because the RDAP lookup failed. firstReleased is the TTS-2 launch entry in the TTS release notes, 5 May 2026. Inworld's TTS-2 page dates general availability to 31 August 2026, and Reasoning shipped on 28 October 2026. ### Terms and privacy, as read A reading by a fixed set of rules, each answered with the vendor's own sentence. Not legal advice. **Terms of service** (https://inworld.ai/terms), read 2026-10-30, dated 2025-06-11, states 6 of the 7 things a reader expects. - Gives the date it was last updated. Last updated 2025-06-11. - Names the governing law or courts. Disputes go to the courts of Santa Clara, California. - States a limit on its liability. Capped at the greater of $100 and the fees paid in the 12 months before the claim. - Says how changes to the terms are announced. Gives 30 days of notice before a change. - Not found in the text. Refers to a service level or uptime commitment. **Privacy policy** (https://inworld.ai/privacy), read 2026-10-30, dated 2026-01-18, states 7 of the 8 things a reader expects. - To know. Says it sells personal data or shares it for advertising. "Some of the activities described in this section may constitute “targeted advertising,” “sharing,” or “selling” under certain laws." - Gives the date it was last updated. Last updated 2026-01-18. - Says how long data is kept. For as long as needed, with no period named. - Says whether personal data is sold or shared for advertising. Says it does not sell personal data. - Gives a privacy contact. privacy@inworld.ai. - Not found in the text. Says where data is transferred or stored. ## Humans behind the project (researched 2026-10-30 from public pages, not part of the grade) ### Key people - Kylan Gibbs, Co-founder and CEO - Ilya Gelfenbeyn, Co-founder - Michael Ermolenko, Co-founder - Note: inworld's realtime tts-2 page, read 30 october 2026, quotes kylan gibbs as ceo of inworld ai. inworld's series a release of 23 august 2022, as published by intel capital, names ilya gelfenbeyn, michael ermolenko and kylan gibbs as founders and ilya gelfenbeyn as ceo at the time. no about or team page was found in the inworld.ai sitemap, so the present roles of the other two founders aren't established and the roster may be incomplete. no personal accounts are linked from inworld's pages, so none are listed. the 28 october 2026 reasoning post is signed by the inworld tts team. the ultravox listing's humans file records inworld's announcement of 30 september 2026 that it acquired ultravox. investors come from the series a release as published by intel capital and from the saas news report of the august 2023 round led by lightspeed. business wire and globenewswire, which carry inworld's own releases, answered robots.txt with 403 and weren't read, so the pre-seed and seed rounds aren't itemised, and meta is listed without a round. the 2023 valuation of over $500 million isn't a stated figure for a named round and is left out, as is the total raised. no later round was found. - Inworld AI (Theai, Inc.): LinkedIn https://www.linkedin.com/company/inworld-ai X https://x.com/inworld GitHub https://github.com/inworld-ai ### Ownership and investors - Backed by: Section 32, Intel, Lightspeed Venture Partners, Founders Fund, Accelerator Investments LLC, First Spark Ventures, Kleiner Perkins, BITKRAFT Ventures, CRV, Microsoft, Micron, LG, SK Telecom, The Venture Reality Fund, HTC, Meta, Stanford University, Samsung ### Getting support - Discord: https://discord.gg/inworld - Support email: support@inworld.ai - Help: https://docs.inworld.ai/portal/support - Help: https://docs.inworld.ai/ - Sources: https://inworld.ai/blog/realtime-tts-2, https://inworld.ai/blog/realtime-tts-2-reasoning-speed-consistency, https://inworld.ai/pricing, https://inworld.ai/terms, https://inworld.ai/security, https://inworld.ai/sitemap.xml, https://docs.inworld.ai/portal/support.md, https://www.intelcapital.com/inworld-ai-closes-50m-series-a-to-populate-video-games-and-the-metaverse-with-interactive-ai-driven-characters/ ## Live (updated 2026-10-31 03:04 UTC) - Right now: up, HTTP 200, 146 ms, checked 2026-10-31 03:04 UTC (get on `https://api.inworld.ai`) - Uptime 24h 100.0% (16 probes) · 30 days 100.0% (16 probes) · p50 158 ms · p95 339 ms - Vendor status page: unknown, no machine-readable status found - Always current: https://www.anchorterminal.com/api/v1/live/inworld-tts.json ## Probe metrics Not measured yet. Our benchmark probes haven't run, so there's no availability, latency or error rate from a run and Performance is pending. Live uptime, where we poll the endpoint, is under Live and doesn't change the score. ## Prices | Item | Price | Unit | Note | | --- | --- | --- | --- | | Realtime TTS-2, On-Demand (free plan, pay as you go) | $25 | per 1M characters | pricing page, checked 30 October 2026 | | Realtime TTS-2 on Growth | $12.50 | per 1M characters | $20 on Creator, $17.50 on Builder, $15 on Developer, from $5 on Enterprise | | Realtime TTS-2 Flash, On-Demand | $15 | per 1M characters | falls to $7 on Growth | | Creator plan | $25 | per month (plan) | $25 in credits a month | | Developer plan | $300 | per month (plan) | $300 in credits a month, priority email support | Across all listings: https://www.anchorterminal.com/prices/index.md ## What a task costs (from the prices above) | Task | Cost | At | | --- | --- | --- | | Narrate a 9,000-character script (about 1,500 words) | $0.11 to $0.22 | Realtime TTS-2 on Growth to Realtime TTS-2, On-Demand (free plan, pay as you go) | The quantity times this listing's own price, from its cheapest item in that unit to its dearest. Plans, minimums and free allowances aren't counted. ## Strengths - Reasoning returns the direction it applied as `reasoningInstruction`, so an agent can log it and reuse it as an inline tag - Per-character prices are public, from $25 per million characters for TTS-2 on the free plan to $12.50 on Growth - REST, HTTP streaming, WebSocket, async jobs and an OpenAI-compatible `/v1/audio/speech` endpoint - llms.txt, Markdown twins of every page and a keyless docs MCP server at docs.inworld.ai/mcp - Single-use client tokens, 15 minutes by default, keep the API key off browsers and phones ## Weaknesses - No OpenAPI or other machine-readable contract was found for the TTS API - API keys can't be limited to TTS. Write toggles cover only the Voice and Router APIs - The 28 October model update replaced `inworld-tts-2` in place, with no dated snapshot to pin - Zero data retention is Enterprise only or a Growth add-on, and the SLA is Enterprise only - The TTS-2 page claims #1 on the Artificial Analysis Speech Arena, which ranked it 8th on 30 October 2026 ## Before you call it (notes for agents) 1. Send the copied Base64 credential as-is in `Authorization: Basic`. Don't encode it again. 2. Set `modelId` explicitly, because SDK defaults may name deprecated models. 3. Keep text under 2,000 UTF-16 units on `/tts/v1/voice` and 4,000 on `voice:stream`, or use an async job. 4. Turn on Reasoning with `synthesisContext.reasoning: REASONING_ON` and store `reasoningInstruction` to repeat a delivery as a bracketed tag. 5. On 429 or error code 8, back off exponentially with jitter. No Retry-After header is documented. ## Connect Install: ```bash npm install @inworld/tts ``` First request: ```bash curl -X POST https://api.inworld.ai/tts/v1/voice -H "Authorization: Basic $INWORLD_API_KEY" -H 'Content-Type: application/json' -d '{"text": "We made it. I honestly did not think we would.", "voiceId": "Dennis", "modelId": "inworld-tts-2", "synthesisContext": {"reasoning": "REASONING_ON"}}' ``` Claude Code: ```bash claude mcp add inworld -- inworld mcp ``` ## Similar tools Ranked by shared capabilities, then score. Same-category tools with no shared capability key are listed last. | Tool | Grade | Score | Rank | Shared capabilities | x402 | Markdown | | --- | --- | --- | --- | --- | --- | --- | | ElevenLabs Text to Speech API + MCP | BB | 75.3 | 60 | speech.tts, speech.streaming, speech.voices, speech.ssml, speech.languages | no | https://www.anchorterminal.com/tools/elevenlabs-tts.md | | Amazon Polly | BB | 73.6 | 91 | speech.tts, speech.streaming, speech.voices, speech.ssml, speech.languages | no | https://www.anchorterminal.com/tools/amazon-polly.md | | Azure AI Speech text-to-speech | BB | 71.5 | 134 | speech.tts, speech.streaming, speech.voices, speech.ssml, speech.languages | no | https://www.anchorterminal.com/tools/azure-text-to-speech.md | | Cartesia Sonic TTS API + MCP | B | 64 | 428 | speech.tts, speech.streaming, speech.voices, speech.ssml, speech.languages | no | https://www.anchorterminal.com/tools/cartesia-tts.md | | Fish Audio TTS API | C | 60.8 | 578 | speech.tts, speech.streaming, speech.voices, speech.languages, voice.clone | no | https://www.anchorterminal.com/tools/fish-audio-tts.md | | VieNeu-TTS v3 Turbo | C | 58.5 | open-weight #74 | speech.tts, speech.voices, speech.languages, speech.streaming, voice.clone | no | https://www.anchorterminal.com/tools/vieneu-tts-v3-turbo.md | ## Panel reviews (0) Reviewed by the Anchor panel (https://www.anchorterminal.com/reviewers/index.md): . Desk reviews, written from public documentation, pricing, terms, source and status history on 1 October 2026. No calls made. For a desk review, the outcome says whether the reviewer's questions could be answered from public material: success, partial or failure. How reviews work: https://www.anchorterminal.com/reviews/how-it-works.md ## Notable - Reasoning, launched on 28 October 2026, is set with `synthesisContext.reasoning: REASONING_ON`. A language model reads the text and an optional `reasoningContext` of up to 600 characters, writes a steering instruction and returns it as `reasoningInstruction` (source: ) - Reasoning runs on `inworld-tts-2` for synchronous, HTTP streaming and async requests. WebSocket, the Realtime API and batch are listed as coming soon (source: ) - The 28 October model update ships behind the same ID, `inworld-tts-2`, and reaches existing integrations as it rolls out by region. No dated snapshot is documented (source: ) - Inline `[tag]` steering covers emotion, pace, pitch, volume and non-verbals such as `[laugh]`, and since 6 August 2026 a tag stays in force until `[reset]` (source: ) - The TTS-2 page shows Realtime TTS-2 as #1 on the Artificial Analysis Speech Arena. Artificial Analysis's provider-voice leaderboard put it 8th, Elo 1,267, on 30 October 2026 (source: ) - Inworld calls TTS-2 with Reasoning the first speech model that decides how to say a line before saying it. That is Inworld's claim (source: ) - Inworld isn't connected to PlayHT. It publishes a migration guide from PlayHT, which the playht-tts listing cites for PlayHT's shutdown dates (source: ) - #10 of 12 in Best text-to-speech APIs for AI agents: https://www.anchorterminal.com/best/text-to-speech/index.md - All 106 tts comparisons: https://www.anchorterminal.com/compare/text-to-speech/index.md ## Compare - [Amazon Polly vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/amazon-polly-vs-inworld-tts.md): BB 73.6 vs C 58.3 - [Azure AI Speech text-to-speech vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-inworld-tts.md): BB 71.5 vs C 58.3 - [Cartesia Sonic TTS API + MCP vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/cartesia-tts-vs-inworld-tts.md): B 64 vs C 58.3 - [Deepgram Text-to-Speech (Aura-2, Flux TTS) vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/deepgram-tts-vs-inworld-tts.md): BB 72.8 vs C 58.3 - [ElevenLabs Text to Speech API + MCP vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/elevenlabs-tts-vs-inworld-tts.md): BB 75.3 vs C 58.3 - [Fish Audio TTS API vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/fish-audio-tts-vs-inworld-tts.md): C 60.8 vs C 58.3 - [HeyGen Voice vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/heygen-voice-vs-inworld-tts.md): BB 71.1 vs C 58.3 - [Inworld Realtime TTS-2 vs Murf TTS API + MCP](https://www.anchorterminal.com/compare/inworld-tts-vs-murf-tts.md): C 58.3 vs BB 70.8 - [Inworld Realtime TTS-2 vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/inworld-tts-vs-playht-tts.md): C 58.3 vs F 4.1 - [Inworld Realtime TTS-2 vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/inworld-tts-vs-resemble-ai-tts.md): C 58.3 vs D 50.3 - [Inworld Realtime TTS-2 vs Rime TTS API + MCP](https://www.anchorterminal.com/compare/inworld-tts-vs-rime-tts.md): C 58.3 vs C 55.9 - [Inworld Realtime TTS-2 vs Soniox Text-to-Speech](https://www.anchorterminal.com/compare/inworld-tts-vs-soniox-tts.md): C 58.3 vs B 63.7 ## Verify this listing For the vendor. The badge or a plain link to this page verifies the listing, from a page on inworld.ai or one of its subdomains. It shows the listing is the vendor's and that the vendor knows it's here, and it never changes a grade, rank or review. The vendor sends the page's address to `POST https://www.anchorterminal.com/api/v1/verify` as `{"slug": "inworld-tts", "url": "…"}`, or calls the `verify_listing` tool at https://www.anchorterminal.com/mcp. We fetch the page once, then again every week; two failed checks in a row and the verification lapses, and a later pass restores it. What we check: https://www.anchorterminal.com/builders/index.md#verify HTML badge: ```html Inworld Realtime TTS-2 on Anchor Terminal ``` Markdown badge, for a README: ```markdown [![Inworld Realtime TTS-2 on Anchor Terminal](https://www.anchorterminal.com/badges/inworld-tts.svg)](https://www.anchorterminal.com/tools/inworld-tts) ``` Plain link: ```html Inworld Realtime TTS-2 on Anchor Terminal ``` ## Share this listing For the vendor. 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