# Google Cloud Text-to-Speech vs Inworld Realtime TTS-2

> Google Cloud Text-to-Speech scores 66.9 (B) to Inworld Realtime TTS-2's 58.3 (C) for text-to-speech. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/google-cloud-tts-vs-inworld-tts
- Markdown: https://www.anchorterminal.com/compare/google-cloud-tts-vs-inworld-tts.md (~5,300 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

Google Cloud Text-to-Speech scores 66.9 (B) on agent readiness against Inworld Realtime TTS-2's 58.3 (C), and leads in 4 of 7 scored categories. Inworld Realtime TTS-2 leads on payments & pricing and maintenance & community. Both do text-to-speech.

- Google Cloud Text-to-Speech: grade B, 66.9/100, rank #351 of 1510. Markdown https://www.anchorterminal.com/tools/google-cloud-tts.md · JSON https://www.anchorterminal.com/api/v1/tools/google-cloud-tts.json
- Inworld Realtime TTS-2: grade C, 58.3/100, rank #756 of 1510. Markdown https://www.anchorterminal.com/tools/inworld-tts.md · JSON https://www.anchorterminal.com/api/v1/tools/inworld-tts.json
- Best text-to-speech APIs for AI agents: https://www.anchorterminal.com/best/text-to-speech/index.md
- All 148 tts comparisons: https://www.anchorterminal.com/compare/text-to-speech/index.md

## Which one, for what

### Google Cloud Text-to-Speech (B)

Good for: Teams already on Google Cloud wanting many languages, SSML and an SLA.

Ahead on:
- Reliability, 85 against 62
- Schema & documentation, 80 against 60
- Security & auth, 80 against 61
- Transparency & trust, 87 against 63

Watch for: No release note since 30 December 2025, though a Gemini 3.1 TTS preview model is listed

### Inworld Realtime TTS-2 (C)

Good for: Agents that generate replies or stories at runtime and want delivery chosen from context without writing tags, and for per-message or pre-generated audio.

Ahead on:
- Payments & pricing, 40 against 20
- Maintenance & community, 68 against 25

Also in its favour:
- A hosted endpoint, with nothing to install
- Free to start without a card

Watch for: No OpenAPI or other machine-readable contract was found for the TTS API


## Why the edge

### Maintenance & community: Inworld Realtime TTS-2 +43

- Google Cloud Text-to-Speech (25): Read as a model. The newest release note is still 30 December 2025 (Chirp 3 HD in yue-HK), 311 days ago, and `gemini-3.1-flash-tts-preview` appears on the Gemini-TTS page with no dated note (0). In the 90 days from 8 August the Python client shipped 2.38.0 on 1 October, whose only change declares Python 3.15 support, which counts half and can't set the recency line (0). Release notes, a public issue tracker and paid support (10 of 15). Official client libraries, Python at 2.38.0 and Node at 7.2.0 (10 of 15). Package CI not checked (5 of 10). Total 25.
- Inworld Realtime TTS-2 (68): 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: Google Cloud Text-to-Speech +24

- Google Cloud Text-to-Speech (87): Closed service under the Google Cloud terms, with Apache-2.0 clients (15). The data logging page, the terms and the privacy notice agree that TTS text and audio aren't logged, and a DPA and sub-processor list exist, as read for google-speech-to-text (25 of 30). Release notes mark preview and GA, and the Cloud terms carry notice before a GA capability is discontinued, but Gemini-TTS is moving to the Agent Platform API with no dated notice for the Cloud TTS models (15 of 20). Regional endpoints (global, us, eu and others) and a public sub-processor list (20). Total 75.
- Inworld Realtime TTS-2 (63): 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.

### Reliability: Google Cloud Text-to-Speech +23

- Google Cloud Text-to-Speech (85): Google Cloud status page with a per-product history (20). None of the four Google Cloud incidents since 8 August (20 August, 1 September, 8 and 9 October, and the europe-west2 incident of 20 October, which listed Speech-to-Text among 38 products) names Text-to-Speech. The public page shows only broad incidents, so clean is read with that limit (30). Quotas published with numbers, 1,000 requests a minute for most voices, 200 for Chirp 3, 500 for Studio, 100 concurrent streams and 100 long-audio requests a minute (15). The quotas page (last updated 26 October 2026) says nothing about the error a breach returns or how to back off, read as google-speech-to-text was (0). A 99.9 per cent monthly SLA with credits of 10, 25 and 50 per cent, read on 6 November (10). Chirp 3 HD and Gemini 2.5 Flash and Pro TTS are GA, with Gemini 3.1 Flash TTS and Flash-Lite in preview (10). 20 + 30 + 15 + 0 + 10 + 10 = 85.
- Inworld Realtime TTS-2 (62): 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). The page is still a script shell on 4 November, and its history wasn't read, because GitHub's pages answer our proxy with 403, 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.

### Schema & documentation: Google Cloud Text-to-Speech +20

- Google Cloud Text-to-Speech (80): Discovery document revision 20260827 with typed methods and 26 schemas, and protocol buffers for gRPC (25). No llms.txt found (0). The Chirp 3 HD and Gemini-TTS pages say which voices suit which use and list formats and limits, but the reference doesn't say when to choose streaming or long audio (15 of 20). Typed messages with enums for encoding and gender and required fields (15). Samples in several languages, standard status codes with little method-specific error detail (10 of 15). Versioned v1 and v1beta1 with dated release notes (15). Total 80.
- Inworld Realtime TTS-2 (60): 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.

### Payments & pricing: Inworld Realtime TTS-2 +20

- Google Cloud Text-to-Speech (20): No x402, MPP or L402 (0). Per-character and per-token prices for every voice family published without a login (20). Monthly free characters (1 million for Chirp 3 HD, 4 million for Standard and WaveNet) need billing enabled, which needs a card (0). A person creates a project and billing account in a browser (0). Total 20.
- Inworld Realtime TTS-2 (40): 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.

### Security & auth: Google Cloud Text-to-Speech +19

- Google Cloud Text-to-Speech (80): Model reading of the checklist, with training and retention in place of the least-privilege and injection lines. OAuth 2.0 with service accounts and IAM roles per project (30). The discovery document lists `access_token`, `oauth_token` and `key` as query parameters, so 10 off, as every Google API listing in this run (20 of 30). The data logging page says Google doesn't log any customer Cloud TTS text or audio (20). The service is stateless and keeps no content (15). Because it is stateless, Data Access audit logs don't apply, leaving admin activity only (5 of 15). Valid security.txt, Google's vulnerability reward programme, SOC 2 and ISO 27001 and public Cloud security bulletins, as on google-speech-to-text (20). Total 80.
- Inworld Realtime TTS-2 (61): 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.

## Score by category

| Category | Weight | Google Cloud Text-to-Speech | Inworld Realtime TTS-2 | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 85 | 62 | Google Cloud Text-to-Speech +23 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 80 | 60 | Google Cloud Text-to-Speech +20 |
| Agent ergonomics | 13% (16.2 this run) | 65 | 68 | Inworld Realtime TTS-2 +3 |
| Security & auth | 14% (17.5 this run) | 80 | 61 | Google Cloud Text-to-Speech +19 |
| Payments & pricing | 10% (12.5 this run) | 20 | 40 | Inworld Realtime TTS-2 +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 25 | 68 | Inworld Realtime TTS-2 +43 |
| Transparency & trust | 7% (8.8 this run) | 87 | 63 | Google Cloud Text-to-Speech +24 |
| Negative events | ≤15 | 0 | -2 | |
| **Total** | | **66.9 · B** | **58.3 · C** | |

## Facts side by side

| Fact | Google Cloud Text-to-Speech | Inworld Realtime TTS-2 |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Google Cloud | Inworld AI |
| Hosted endpoint | no (local only) | `https://api.inworld.ai` |
| Transports | HTTP | HTTP, websocket |
| Auth | OAuth | API key |
| Pricing | Pay per use | Freemium |
| Price for text-to-speech | $10 per 1M tokens | $12.50 per 1M characters |
| x402 | no | no |
| Licence | none | Proprietary service under Inworld's Terms of Service. The Node.js SDK `@inworld/tts` and the CLI `@inworld/cli` are MIT on npm |
| Tools exposed | 0 | none |
| Read-only variant documented | no | no |
| llms.txt | no | yes |
| Last release | 2025-12-30 | 2026-10-28 |
| Terms last updated | 2026-09-02 | 2025-06-11 |
| Privacy policy last updated | 2026-10-01 | 2026-01-18 |
| Customer content may train models | yes | not found in the text |
| Terms restrict automated access | not found in the text | not found in the text |
| Terms restrict benchmarking | not found in the text | 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 | not found in the text | not found in the text |
| Popularity | none | 3.6k npm/wk |

## What the same task costs

| Task | Google Cloud Text-to-Speech | Inworld Realtime TTS-2 |
| --- | --- | --- |
| Narrate a 9,000-character script | $0.04 to $1.44 | $0.11 to $0.22 |

## Verdicts

**Google Cloud Text-to-Speech.** Cloud TTS has a typed discovery document, a 99.9 per cent SLA, no logging of text or audio, and voices from $4 to $160 per million characters. Its release notes stop at 30 December 2025, the newest Gemini TTS models ship only on the Agent Platform API, and tokens can travel in the URL.

**Inworld Realtime TTS-2.** 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 4 November.

## Before you call either

### Google Cloud Text-to-Speech

1. Send OAuth tokens in the Authorization header, never as `access_token` or `key` in the URL
2. Use `synthesizeLongAudio` with a Cloud Storage bucket for long text, and `text:synthesize` for short replies
3. Pick Chirp 3 HD for natural voices with SSML, and Gemini-TTS when the delivery needs prompt steering
4. Check whether the Gemini TTS model you want is on the Cloud TTS API or only on the Agent Platform API
5. Stay within 200 requests a minute on Chirp 3 voices, which have their own quota

### Inworld Realtime TTS-2

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.

## Questions

### Which is better for AI agents, Google Cloud Text-to-Speech or Inworld Realtime TTS-2?

Google Cloud Text-to-Speech scores 66.9 (B) on agent readiness against Inworld Realtime TTS-2's 58.3 (C), and leads in 4 of 7 scored categories. Inworld Realtime TTS-2 leads on payments & pricing and maintenance & community.

### Do Google Cloud Text-to-Speech and Inworld Realtime TTS-2 need an API key?

Google Cloud Text-to-Speech uses an OAuth sign-in. Inworld Realtime TTS-2 needs an API key.

### Can an agent call Google Cloud Text-to-Speech and Inworld Realtime TTS-2 without installing anything?

No hosted endpoint is listed for Google Cloud Text-to-Speech. Inworld Realtime TTS-2 has a hosted endpoint at https://api.inworld.ai.


## For agents

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

## Other comparisons with Google Cloud Text-to-Speech or Inworld Realtime TTS-2

- [Amazon Polly vs Google Cloud Text-to-Speech](https://www.anchorterminal.com/compare/amazon-polly-vs-google-cloud-tts.md)
- [Amazon Polly vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/amazon-polly-vs-inworld-tts.md)
- [Azure AI Speech text-to-speech vs Google Cloud Text-to-Speech](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-google-cloud-tts.md)
- [Azure AI Speech text-to-speech vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/azure-text-to-speech-vs-inworld-tts.md)
- [Cartesia Sonic TTS API + MCP vs Google Cloud Text-to-Speech](https://www.anchorterminal.com/compare/cartesia-tts-vs-google-cloud-tts.md)
- [Cartesia Sonic TTS API + MCP vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/cartesia-tts-vs-inworld-tts.md)
- [Deepgram Text-to-Speech (Aura-2, Flux TTS) vs Google Cloud Text-to-Speech](https://www.anchorterminal.com/compare/deepgram-tts-vs-google-cloud-tts.md)
- [Deepgram Text-to-Speech (Aura-2, Flux TTS) vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/deepgram-tts-vs-inworld-tts.md)
- [ElevenLabs Text to Speech API + MCP vs Google Cloud Text-to-Speech](https://www.anchorterminal.com/compare/elevenlabs-tts-vs-google-cloud-tts.md)
- [ElevenLabs Text to Speech API + MCP vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/elevenlabs-tts-vs-inworld-tts.md)
- [Fish Audio TTS API vs Google Cloud Text-to-Speech](https://www.anchorterminal.com/compare/fish-audio-tts-vs-google-cloud-tts.md)
- [Fish Audio TTS API vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/fish-audio-tts-vs-inworld-tts.md)
- [Google Cloud Text-to-Speech vs HeyGen Voice](https://www.anchorterminal.com/compare/google-cloud-tts-vs-heygen-voice.md)
- [Google Cloud Text-to-Speech vs MiniMax Speech (T2A)](https://www.anchorterminal.com/compare/google-cloud-tts-vs-minimax-speech.md)
- [Google Cloud Text-to-Speech vs Murf TTS API + MCP](https://www.anchorterminal.com/compare/google-cloud-tts-vs-murf-tts.md)
- [Google Cloud Text-to-Speech vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/google-cloud-tts-vs-playht-tts.md)
- [Google Cloud Text-to-Speech vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/google-cloud-tts-vs-resemble-ai-tts.md)
- [Google Cloud Text-to-Speech vs Rime TTS API + MCP](https://www.anchorterminal.com/compare/google-cloud-tts-vs-rime-tts.md)
- [Google Cloud Text-to-Speech vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/google-cloud-tts-vs-smallest-lightning-tts.md)
- [Google Cloud Text-to-Speech vs Soniox Text-to-Speech](https://www.anchorterminal.com/compare/google-cloud-tts-vs-soniox-tts.md)
- [HeyGen Voice vs Inworld Realtime TTS-2](https://www.anchorterminal.com/compare/heygen-voice-vs-inworld-tts.md)
- [Inworld Realtime TTS-2 vs MiniMax Speech (T2A)](https://www.anchorterminal.com/compare/inworld-tts-vs-minimax-speech.md)
- [Inworld Realtime TTS-2 vs Murf TTS API + MCP](https://www.anchorterminal.com/compare/inworld-tts-vs-murf-tts.md)
- [Inworld Realtime TTS-2 vs PlayHT Text-to-Speech API](https://www.anchorterminal.com/compare/inworld-tts-vs-playht-tts.md)
- [Inworld Realtime TTS-2 vs Resemble AI Text-to-Speech API](https://www.anchorterminal.com/compare/inworld-tts-vs-resemble-ai-tts.md)
- [Inworld Realtime TTS-2 vs Rime TTS API + MCP](https://www.anchorterminal.com/compare/inworld-tts-vs-rime-tts.md)
- [Inworld Realtime TTS-2 vs Smallest.ai Lightning TTS](https://www.anchorterminal.com/compare/inworld-tts-vs-smallest-lightning-tts.md)
- [Inworld Realtime TTS-2 vs Soniox Text-to-Speech](https://www.anchorterminal.com/compare/inworld-tts-vs-soniox-tts.md)

---

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