Google Cloud Text-to-Speech API
Browse all Google APIs41
AI ReadinessFoundational (D-)41/100
Official vendor OpenAPI document · agent-readyAI/MLSpeechoauth27 EndpointsREST
For Agents
Synthesize natural-sounding speech audio from text or SSML in 50+ languages, including long-form Cloud Storage output and a wide voice catalog.
Use for: I need to convert text to speech audio in MP3 format, Synthesize a long audiobook chapter to a Cloud Storage bucket, List all available English voices, Generate speech with SSML for a custom pronunciation
Not supported: Does not handle speech recognition, audio editing, or voice cloning of arbitrary speakers - use for synthesising speech from text using Google's voice catalog only.
Cloud Text-to-Speech synthesises natural-sounding speech from text or SSML using Google's neural network voices, including WaveNet, Neural2, and Studio voice tiers. It supports more than 50 languages and locales, dozens of voice variants per language, and SSML controls for pacing, pitch, pauses, and pronunciation. The synchronous synthesize endpoint returns audio for short text; the synthesizeLongAudio endpoint streams long-form audio (audiobooks, course content) to a Cloud Storage bucket via a long-running operation.
Install Jentic One Beta
Connect the Cloud Text-to-Speech API to your agent
Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the Cloud Text-to-Speech API, or any other public or private API you need. You set the rules, the agent never sees your credentials, and every call is logged.
Two steps, two machines. Install the instance in a safe environment, then register your agent from wherever it runs.
1
Step 1: Jentic One Host machine
# On the machine that will host your Jentic One instance:
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Fgoogleapis.com%2Ftexttospeech" | sh2
Step 2: Agent machine
# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Fgoogleapis.com%2Ftexttospeech" | sh
jentic register # connects your agent to your Jentic One instanceJentic One is in public beta. The setup above keeps your agent separate from the instance, which is what you want before using real credentials: an agent running as the same OS user as Jentic One can read its stored keys directly. Just evaluating? A single local install is fine to start. See the secure deployment guide for the tiers.
Capabilities
What an agent can do with Cloud Text-to-Speech API.
Synthesize short-form speech audio from plain text or SSML markup
Stream long-form audio synthesis output to a Cloud Storage bucket
List available voices filtered by language and gender
Apply SSML controls for pacing, pitch, pauses, emphasis, and pronunciation
Choose between Standard, WaveNet, Neural2, and Studio voice quality tiers
Track long-running synthesis operations through dedicated operation endpoints
Use Cases
Patterns agents use Cloud Text-to-Speech API for, with concrete tasks.
★ IVR and Voice Bot Prompts
Contact centres use Cloud Text-to-Speech to generate dynamic prompts for IVR systems and voice bots. Static greetings are pre-rendered with a Studio voice and cached; per-call dynamic text (caller name, account balance) is synthesised on demand using lower-latency Neural2 voices. Output is returned as base64 LINEAR16 audio that integrates with telephony stacks like Dialogflow CX or Twilio.
POST /v1/text:synthesize with input.text='Welcome back, Maria. Your balance is $312.', voice.languageCode='en-US', voice.name='en-US-Neural2-F', and audioConfig.audioEncoding='LINEAR16'.
Audiobook and Long-Form Narration
Publishers convert book chapters and course transcripts into audio using the synthesizeLongAudio endpoint. The endpoint accepts up to 1 million characters per request, runs as a long-running operation, and writes the resulting audio file directly to a Cloud Storage bucket. This avoids the synchronous endpoint's 5,000-character limit and is the production-grade path for any content longer than a paragraph.
POST /v1/{parent=projects/*/locations/*}:synthesizeLongAudio with the chapter text, parent=projects/PROJECT/locations/us-central1, and outputGcsUri='gs://my-bucket/chapter-1.wav'.
Multilingual Marketing Voice-Overs
Marketing teams generate localised voice-overs for product videos by sending the same script translated into target languages and selecting a matching Neural2 or Studio voice per locale. This produces consistent brand voice characteristics across markets in minutes rather than scheduling voice talent per language.
Iterate over a list of language-text pairs and POST /v1/text:synthesize for each with voice.languageCode set per locale and voice.name=<lang>-Studio-A.
Agent-Generated Spoken Responses via Jentic
An AI agent producing voice replies for a smart-home assistant generates the response text from an LLM, then calls Cloud Text-to-Speech through Jentic to render audio. Jentic isolates the GCP credential, returns the audio bytes, and the agent streams them to the smart speaker.
Through Jentic, search 'synthesize speech from text', load POST /v1/text:synthesize, and execute it with the LLM-generated reply text and a chosen Neural2 voice.
Key Endpoints
7 endpoints — cloud text-to-speech synthesises natural-sounding speech from text or ssml using google's neural network voices, including wavenet, neural2, and studio voice tiers.
METHOD
PATH
DESCRIPTION
POST
/v1/text:synthesize
Synthesize speech audio from text or SSML
GET
/v1/voices
List available voices, optionally filtered by language code
POST
/v1/{+parent}:synthesizeLongAudio
Start a long-running synthesis writing to Cloud Storage
GET
/v1/{+name}/operations
List long-running synthesis operations
POST
/v1/{+name}:cancel
Cancel an in-flight long-running synthesis
POST
/v1/text:synthesize
Synthesize speech audio from text or SSML
GET
/v1/voices
List available voices, optionally filtered by language code
POST
/v1/{+parent}:synthesizeLongAudio
Start a long-running synthesis writing to Cloud Storage
GET
/v1/{+name}/operations
List long-running synthesis operations
POST
/v1/{+name}:cancel
Cancel an in-flight long-running synthesis
Jentic AI Readiness Score
This API is usable in Jentic One now. Its AI-readiness score against Jentic's framework shows where it stands today and where improvements would make it even easier for agents to use.
C
Cloud Text-to-Speech API
- Foundational (D-)41/100
71
Foundational Compliance56
Developer Experience & Jentic Compatibility18
AI-Readiness & Agent Experience94
Agent Usability63
Security59
AI DiscoverabilityPowered by JenticScoring Framework 1.0.0 | Scoring Engine 0.4.0
Show dimension breakdown
71
Foundational Compliance
Base layer of spec validity and structural soundness.
Grade: A-Signals: 4
84%
Lint Results
Aggregated quality score from linter diagnostics, weighted by severity.
100%
Resolution Completeness
Percentage of `$ref` references that resolve successfully.
0%
Specification Validity
Checks whether the API description parses successfully and conforms to its declared specification (e.g., OpenAPI).
100%
Structural Integrity
Structural correctness score based on schema issues using logarithmic dampening.
56
Developer Experience & Jentic Compatibility
Clarity, completeness, and ingestion readiness for developers and tooling.
Grade: CSignals: 4
0%
Example Density
How richly the API is illustrated with examples.
100%
Example Validity
Percentage of examples that conform to their schemas.
25%
Response Coverage
Percentage of operations with complete response definitions (success, client error, server error).
100%
Tooling Readiness
Health of API ingestion, bundling, and resolution within Jentic pipelines.
18
AI-Readiness & Agent Experience
Semantic breadth, depth, and agent comprehension for AI systems.
Grade: FSignals: 4
74%
Description Coverage
Coverage of descriptions across API elements.
0%
Error Standardization
Coverage of RFC 9457 Problem Details for error responses.
0%
OperationId Quality
Coverage, uniqueness, and casing consistency of operationIds for AI inference.
0%
Summary Coverage
Coverage of summaries across operations/tags/info.
94
Agent Usability
Functional utility, complexity comfort, and AI orchestration readiness.
Grade: A+Signals: 1
94%
Complexity Comfort
Agent comfort level based on API operational and structural complexity.
63
Security
Trust, risk posture, and security compliance.
Grade: B-Signals: 1
62%
Authentication Strength
Average quality of security schemes based on authentication method strength (weakest link for OAuth2).
59
AI Discoverability
Findability, semantic richness, and reasoning readiness.
Grade: C+Signals: 1
59%
Descriptive Richness
Clarity and depth of descriptions across API elements.
Score it yourself
Every API in the directory is allowlisted, so you can re-score it with no key required.
npx @jentic/api-scorecard-cli score <openapi-url>Why Jentic?
What agents get from Jentic-routed access to this vendor.
Setup
Wiring the Cloud Text-to-Speech API by hand means setting up a Google service account, granting the cloud-platform scope, formatting the input, voice, and audioConfig blocks, and tracking long-audio operations yourself. Through Jentic you install once, import the Cloud Text-to-Speech API from the API Directory, store the service-account credential once, and your agent calls it.
Permission scoping
The text to synthesize travels in the request body rather than a resource path, so scope by operation: limit the agent to the operations it needs, such as text:synthesize and listing voices. You choose the operations it may call, so long-audio synthesis is not included unless you add it.
Credential isolation
Your Cloud Text-to-Speech service-account credential is stored once, encrypted, by your own Jentic One instance and injected at execution time. It never enters the agent's prompt, logs, or context.
Intent-based discovery
Agents search Jentic by intent such as 'synthesize speech from text' or 'list available voices', and Jentic returns the matching Text-to-Speech v1 operation with its input schema, including input, voice, and audioConfig, so the agent calls the right endpoint without browsing the reference docs.
Related APIs
Alternatives and complements available in the Jentic catalogue.
FAQs
Specific to using Cloud Text-to-Speech API through Jentic.
What authentication does the Cloud Text-to-Speech API use?
OAuth 2.0 with the cloud-platform scope is required. Most production integrations use a Google Cloud service-account credential and exchange it for a short-lived bearer token. Through Jentic, the service-account JSON is stored encrypted in the vault and Jentic mints scoped tokens per call.
Can I synthesize long-form audio with the Cloud Text-to-Speech API?
Yes. The synchronous /v1/text:synthesize endpoint caps input at 5,000 characters; for longer content use POST /v1/{parent}:synthesizeLongAudio, which accepts up to 1 million characters per request and writes the resulting audio to a Cloud Storage URI you specify. Track progress via the returned long-running operation.
What are the rate limits for the Cloud Text-to-Speech API?
The default per-project quota is 1,000 requests per minute for the synchronous synthesize endpoint, with separate character-per-minute caps that vary by voice tier (Standard voices have higher throughput than Studio). Long-audio synthesis allows a smaller number of concurrent operations. Quota increases are available through the Cloud Console.
How do I generate speech audio through Jentic?
Search Jentic for 'synthesize speech from text', load POST /v1/text:synthesize, and execute it with input.text, voice (languageCode and optional name), and audioConfig.audioEncoding (MP3, LINEAR16, OGG_OPUS). The response includes audioContent as base64. Get started with Jentic One, the self-hosted execution layer.
What voice tiers and languages are supported?
Standard, WaveNet, Neural2, and Studio voice tiers are available across more than 50 languages. Studio voices offer the highest realism and are recommended for narration; Neural2 balances quality and latency for interactive use; WaveNet is a long-standing high-quality tier; Standard is the cheapest and lowest-latency. List all available voices via GET /v1/voices.
Is the Cloud Text-to-Speech API free?
Pricing is per-character with a free tier each month. Standard voices and WaveNet/Neural2 voices have separate free-tier allotments; Studio voices have their own pricing. SSML markup is included in the character count. See cloud.google.com/text-to-speech/pricing for current rates.
Can I limit what my agent is allowed to do with the Cloud Text-to-Speech API?
Yes. Because you run Jentic One yourself, your own rules decide which operations and credentials the agent may use, and the text to synthesize travels in the request body rather than a resource path, so you scope by operation. You can allow the agent only the operations it needs, such as text:synthesize and listing available voices with GET /v1/voices, and leave everything else off. Long-audio synthesis via synthesizeLongAudio, which writes to a Cloud Storage bucket, stays unavailable to the agent unless you explicitly add it. Your service-account credential is injected at execution time and never reaches the agent's prompt or logs.
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