> ## Documentation Index > Fetch the complete documentation index at: https://docs.pyai.com/llms.txt > Use this file to discover all available pages before exploring further. # Synthesize speech > OpenAI-compatible text-to-speech. Returns audio bytes. The serving adapter defaults to incremental delivery from the streaming lane. Set `stream: false` when you require a complete buffered body with `Content-Length`. Requires the `speak:synthesize` scope. ## OpenAPI ````yaml https://api.pyai.com/openapi.json post /v1/audio/speech openapi: 3.1.0 info: title: PyAI API version: 2.4.0 description: >- Telephony-native Voice AI behind one bearer key: - **Hear**, speech-to-text · `POST /v1/audio/transcriptions` (streaming + batch) - **Speak**, text-to-speech · `POST /v1/audio/speech`, `GET /v1/voices` - **Clone**, custom voices from a short clip · `/v1/voice/clones` - **Cast**, auto-directed expressive voiceovers · `/v1/cast` - **Dub**, asynchronous English-to-Hindi audio dubbing · `POST /v1/dub` ([guide](https://docs.pyai.com/guides/dub-overview)) - **Cue (not active on the serving stream)**, reserved grounding configuration for `GET /v1/audio/transcriptions/stream` - **Omni**, full-duplex agentic voice (speech-to-speech, grounded in your knowledge bases + tools) · `/v1/omni` - **Knowledge Bases**, hosted grounding for Omni: create bases, add documents (file, URL, or text), crawl a public website, bind to agents or org defaults · `/v1/knowledgebases` - **AMD API**, answering-machine detection: know *who or what* answered a call (human, voicemail, IVR, iPhone/Google screening, dead number) with the reason it decided · `wss …/v1/amd/stream` (Twilio Media Streams drop-in), `POST /v1/amd/config`, `GET /v1/amd/calls/{id}` - **Agents Beta**, the live console feature to create, configure, test, and connect Omni voice agents without code. Beta features and limits may change. ## Authentication Create a key in the [console](https://console.pyai.com) (it is shown once) and send it as a bearer token: ``` Authorization: Bearer pyai_live_... ``` Keys are environment-scoped: `pyai_live_...` (production) and `pyai_test_...` (sandbox). `POST /v1/sandbox/keys` creates an instant, short-lived test key without login or billing. Account signup also creates a sandbox key. Live keys consume prepaid credit; phone verification may unlock promotional credit under graduated-signup rules, but credit is not guaranteed at signup. Keys are self-validating signed tokens: they work on every PyAI surface the instant they are created, no activation or propagation delay. Treat them as opaque strings (up to 512 chars) and never parse their contents. WebSocket endpoints can't use request headers from a browser, so pass the key as a **subprotocol** instead: ``` Sec-WebSocket-Protocol: pyai.v1, pyai-key.pyai_live_... ``` (server-side clients may instead append `?api_key=...` to the URL). Your key is authenticated on the upgrade and never reaches the model. ## Quickstart, Hear (speech-to-text) ``` curl https://api.pyai.com/v1/audio/transcriptions \ -H "Authorization: Bearer $PYAI_API_KEY" \ -F file=@audio.wav -F model=pyai-hear # -> { "text": "..." } ``` ## Quickstart, Speak (text-to-speech) ``` curl https://api.pyai.com/v1/audio/speech \ -H "Authorization: Bearer $PYAI_API_KEY" \ -H "Content-Type: application/json" \ -d '{"model":"pyai-speak","input":"Hello from PyAI.","voice":"voice_abc"}' \ --output speech.wav ``` `voice` is a stock voice id from `GET /v1/voices` (the curated prebuilt catalog with personas and avatars) or a cloned voice id from `/v1/voice/clones`. Omit it to use the platform default voice (`stock_dorit_en_us`). ## Quickstart, Omni (realtime voice agent) Omni is **zero-state, there is nothing to create first.** Open a WebSocket, pass your key as a subprotocol, and send the agent's behavior (voice, persona, knowledge endpoint) in the first `configure` frame: ``` wss://api.pyai.com/v1/omni?session_label=support&format=pcm16&rate=24000 Sec-WebSocket-Protocol: pyai.v1, pyai-key.$PYAI_API_KEY ``` The session is authorized by your key's **organization**; `session_label` is an **optional, opaque** tag (echoed to your own knowledge endpoint for correlation), omit it or use any value. When `session_label` equals a **`/v1/agents` profile id**, the engine loads persona, voice, and **greeting message** from that profile (turn-0 playback). `format` and `rate` are load-bearing on the connect URL (the SDK sets them). Prefix each PCM16 frame with byte `0x01`; prefix control JSON with byte `0x03`. **Optional convenience:** pre-store config via `POST /v1/agents` (including `greeting`, `consent_line`, `recordings_enabled`) and pass its id as `session_label`, or send everything inline in the post-handshake `configure` frame. Not required to connect. For reproducible eval runs, determinism controls (`seed`/`temperature`) ride the Omni session's `configure` frame, which the gateway passes through unchanged, they are honored once the engine supports them; no platform change is required. ## Scopes | Scope | Grants | | --- | --- | | `hear:transcribe` | `POST /v1/audio/transcriptions` | | `hear:stream` | `GET /v1/audio/transcriptions/stream` (WebSocket) | | `hear:configure` | `GET`/`PUT /v1/hear/vocabulary` | | `speak:synthesize` | `POST /v1/audio/speech` (Speak) | | `speak:clone` | `/v1/voice/clones` (Clone) | | `speak:design` | `/v1/voice/design` (Speak) | | `omni:session` | `/v1/omni` and `POST /v1/omni/sessions` (mint a browser session token) | | `omni:read` | `/v1/omni/calls` (Omni post-call records) | | `kb:manage` | `/v1/knowledgebases/*` (hosted knowledge bases for Omni grounding) | | `transcribe:jobs` | `/v1/transcription/jobs` | | `trace:configure` | `/v1/trace/config`, `/v1/trace/rule-packs` (Trace management) | | `trace:read` | `/v1/trace/interactions`, `/violations`, `/findings`, `/exposure` (Trace reads) | | `recap:configure` | `/v1/recap/config` (Recap management) | | `recap:configure` | `/v1/recap/crm-config` (Salesforce field mapping) | | `recap:read` | `/v1/recap/calls` (Recap reads and speaker-role corrections) | | `amd:detect` | `wss …/v1/amd/stream` (AMD realtime detection, Twilio drop-in) | | `amd:configure` | `/v1/amd/config` (AMD operating-point dial + webhook) | | `amd:read` | `/v1/amd/calls` (AMD decision records) | | `telephony:manage` | `/v1/telephony/*` (managed numbers) | `GET /v1/models`, `GET /v1/voices`, and `GET /v1/me` need no specific scope, any active key may call them. Wildcards (`hear:*`, `speak:*`, …, and the global `*`) grant every scope in their family. ## Canonical endpoints One row per product surface, endpoint, auth, required scope, and lifecycle status. **live** = generally available; **beta** = available now with features or limits that may change; **unavailable** = reserved in the contract but not active on the serving route. | Product | Endpoint | Auth | Scope | Status | | --- | --- | --- | --- | --- | | Identity | `GET /v1/me` | Bearer | _any active key_ | live | | Models | `GET /v1/models` | Bearer | _any active key_ | live | | Voices | `GET /v1/voices`, `GET /v1/voices/{id}` | Bearer | _any active key_ | live | | Hear (batch) | `POST /v1/audio/transcriptions` | Bearer | `hear:transcribe` | live | | Hear (vocabulary settings) | `GET`/`PUT /v1/hear/vocabulary` | Bearer | `hear:configure` | live | | Hear (streaming) | `GET /v1/audio/transcriptions/stream` (WS) | Subprotocol | `hear:stream` | live | | Cue | `GET /v1/audio/transcriptions/stream` + grounding (WS) | Subprotocol | `hear:stream` | unavailable | | Hear (async batch) | `POST`/`GET /v1/transcription/jobs` | Bearer | `transcribe:jobs` | live | | Speak (TTS) | `POST /v1/audio/speech` | Bearer | `speak:synthesize` | live | | Clone | `GET`/`POST /v1/voice/clones` | Bearer | `speak:clone` | live | | Speak (design) | `/v1/voice/design` | Bearer | `speak:design` | live | | Omni | `wss …/v1/omni?session_label=` | Subprotocol | `omni:session` | live | | Agent profiles (optional config) | `/v1/agents`, `/v1/agents/{id}` | Bearer | `omni:session` | live | | Knowledge Bases (hosted grounding) | `/v1/knowledgebases/*`, `PUT /v1/agents/{id}/knowledgebases` | Bearer | `kb:manage` (`omni:session` for the binding) | live | | Trace (config) | `/v1/trace/config`, `/v1/trace/rule-packs` | Bearer | `trace:configure` | beta | | Trace (reads) | `/v1/trace/interactions`, `/violations`, `/findings`, `/exposure` | Bearer | `trace:read` | beta | | Recap (config) | `/v1/recap/config` | Bearer | `recap:configure` | live | | Recap (CRM) | `/v1/recap/crm-config` | Bearer | `recap:configure` | live | | Integrations (Zapier) | `/v1/integrations/events`, `/v1/integrations/zapier/hooks` | Bearer | _any active key_ | live | | Recap (reads) | `/v1/recap/calls` | Bearer | `recap:read` | live | | Omni call records | `/v1/omni/calls`, `/v1/omni/calls/{id}` | Bearer | `omni:read` | live | | AMD (stream) | `wss …/v1/amd/stream` (Twilio Media Streams drop-in) | TwiML `` (from Twilio) or subprotocol (server-side) | `amd:detect` | live | | AMD (config) | `GET`/`POST /v1/amd/config` | Bearer | `amd:configure` | live | | AMD (reads) | `GET /v1/amd/calls`, `/v1/amd/calls/{id}` | Bearer | `amd:read` | live | | Telephony | `/v1/telephony/*` | Bearer | `telephony:manage` | live | | Agents (console builder) | `https://console.pyai.com/agents` | Console session |, | beta | WebSocket surfaces authenticate with the `Sec-WebSocket-Protocol: pyai.v1, pyai-key.` subprotocol pair (or `?api_key=` server-side); everything else takes the `Authorization: Bearer` key. Managed-number calls return 404 until the PyAI network is enabled for the account. ## Rate limits & billing Every key has a per-second rate limit (with burst) and a cap on concurrent realtime sessions. Exceeding either returns `429` with a `Retry-After` header. Usage is metered per minute of audio, transcription minutes (Hear), synthesized audio minutes (Speak), and realtime session minutes (Omni), and billed against your plan and credits. List prices: Hear $0.001/min (async Transcribe $0.0005/min), Speak $0.04/min, Omni $0.05/min including speech plus brain, and Agents Live Beta $0.08/min. Managed telephony is separate at $0.01/min. English Natural (`en1`) is available on Speak (streaming and buffered) and Omni; Omni acknowledges the canonical id and `voice_tier: natural`. Hindi uses the Standard-tier voices `hi1`–`hi4` on Omni; the former Hindi Natural aliases (`hi5`–`hi8`) are retired and no longer in the catalog. Standard and Natural voices are included in their product's base rate with no voice-tier add-on. The AMD API bills per **answered** call, the first 5,000 answered calls each month are free, then $0.004/answered call (no-answers, busies, and failed calls are free; AMD bundled with PyAI telephony/Omni is included at no charge). AI products (Hear, Speak, Omni) bill **per second by default**, the pulse is applied once to each meter's invoice-period total, so many short sessions are summed and rounded a single time (never minute-rounded per call), and an empty/failed call bills nothing. Coarser pulses are available as an optional enterprise override. Managed telephony minutes keep a 1-minute pulse. Per-character Speak billing is available on enterprise contracts. contact: name: PyAI url: https://pyai.com servers: - url: https://api.pyai.com description: Production security: - apiKey: [] - xApiKey: [] tags: - name: Dub description: >- Asynchronous audio dubbing into Hindi: submit a recording, poll the job and download the output. - name: Omni description: >- The flagship: build an AI voice agent with one WebSocket (`GET /v1/omni`) and one `configure` frame, nothing to pre-create. This group also holds the optional browser-token mint and the post-call records. - name: Knowledge Bases description: >- Hosted knowledge bases for Omni grounding: create a base, add documents (file upload, URL fetch, or pasted text), then bind it to agent profiles or set org-wide defaults. Bound bases are retrieved per turn, no `kb_endpoint` of your own required. - name: Identity description: >- Introspect the calling key: org/project, env, granted scopes, and limits/credit posture. Use it to self-diagnose a 401/403/402. - name: Speech To Text (Hear) description: Speech-to-text (streaming + batch) - name: Text To Speech (Speak) description: Text-to-speech, stock voices, and prompt-to-voice design - name: Clone description: Enroll, list, and delete custom voices from a short reference clip - name: Models description: Model catalog - name: Sandbox description: >- Zero-friction onboarding for coding agents: mint a free, instant, no-card sandbox key with no human steps. - name: Startup Program description: >- PyAI for Startups: $20k to $100k in PyAI credit for early-stage voice teams. Public application endpoint; review and activation happen out of band. - name: Cast description: >- Auto-directed, expressive multi-line voiceover projects and asynchronous renders. - name: Transcription Jobs description: Async batch transcription - name: Agents description: >- Agent profiles used by the live Agents Beta console and available directly through the API. Store Omni session config (persona, greeting, voice, conversation knobs) and reference it by id instead of sending a full `configure` frame each call. Profiles remain optional for direct `/v1/omni` integrations. - name: Trace description: >- Compliance & guardrails: per-agent config, rule packs, and the exposure / violations / interaction-evidence read views - name: AMD description: >- Answering-machine detection: know who or what answered a call (human, voicemail, IVR, iPhone/Google screening, dead number), with the reason it decided. Twilio Media Streams drop-in over `wss …/v1/amd/stream`; one operating-point dial; billed per answered call. - name: Telephony description: >- Managed phone numbers: search, provision, route to an agent, and release. Call minutes bill on telephony.minutes ($0.01/min). - name: WhatsApp description: >- WhatsApp Business Calling: register a WhatsApp Business number, enable calling, and let an Omni agent answer (and, with the user's permission, place) WhatsApp voice calls. Requires the `telephony:manage` scope. - name: Call Integrations description: >- Signed provider webhooks that import completed calls into Hear, Recap, and offline Trace. paths: /v1/audio/speech: post: tags: - Text To Speech (Speak) summary: Synthesize speech description: >- OpenAI-compatible text-to-speech. Returns audio bytes. The serving adapter defaults to incremental delivery from the streaming lane. Set `stream: false` when you require a complete buffered body with `Content-Length`. Requires the `speak:synthesize` scope. operationId: createSpeech requestBody: required: true content: application/json: schema: type: object required: - input properties: model: type: string default: pyai-speak description: >- Use `pyai-speak`. The OpenAI `tts-1` and `tts-1-hd` aliases remain accepted for drop-in compatibility. input: type: string maxLength: 2000 description: >- Text to synthesize. Maximum 2000 characters; longer text answers `400 input_too_long` naming the limit and the length you sent. Split longer scripts into several requests. voice: type: string description: >- A stock voice id from `GET /v1/voices` (e.g. `stock_dorit_en_us`) or a cloned voice id (e.g. `voice_abc`) created via `/v1/voice/clones`. Omit to use the platform default voice (`stock_dorit_en_us`). For drop-in OpenAI compatibility, the preset names `alloy`, `echo`, `fable`, `onyx`, `nova`, and `shimmer` are also accepted and map to PyAI stock voices. response_format: type: string enum: - wav - mp3 - opus - aac - flac - pcm - g711_ulaw - g711_alaw default: wav description: >- Output audio format. The response `Content-Type` varies by format (`audio/wav`, `audio/mpeg`, `audio/ogg`, `audio/aac`, `audio/flac`, `audio/pcm`, `audio/basic`). `pcm` returns raw, headerless 16-bit little-endian mono samples (no container) at `sample_rate`, the format voice-agent orchestrators (e.g. Vapi custom-voice, LiveKit/Pipecat) feed directly into their pipelines. `g711_ulaw`/`g711_alaw` return raw, headerless G.711 telephony audio at a fixed 8 kHz mono (for Twilio/Plivo/FreeSWITCH); `sample_rate` does not apply and is rejected unless set to `8000`. sample_rate: type: integer minimum: 8000 maximum: 48000 description: >- Optional output sample rate in Hz (8000-48000), e.g. `8000`/`16000` for telephony or `24000` for wideband. Omit to use the native 24 kHz. Most relevant with `response_format: pcm`. Does not apply to `g711_ulaw`/`g711_alaw`, which are always 8 kHz mono (a conflicting value is rejected). speed: type: number description: >- Reserved but not active on Speak. Sending this field currently returns `400 unsupported_parameter`. emotion: type: string description: >- Optional emotion for voices that support expressive rendering (cloned voices and the multilingual natural tier): one of `neutral`, `happy`, `sad`, `angry`, `fearful`, `surprised`. The emotion is rendered in the same voice. Voices that do not support it reject the field with `unsupported_parameter`. Intensity is not exposed on Speak; use Cast for graded intensity. stream: type: boolean default: true description: >- Use incremental audio delivery. The default is `true`: the adapter forwards validated chunks as they arrive. Set `false` to use the blocking lane and receive a complete buffered body with a `Content-Length`. Every catalog voice accepts both values. A voice whose serving fleet has no streaming lane is rendered on the blocking lane and the response carries `x-pyai-stream: buffered` — same body, same format, higher time-to-first-byte. seed: type: integer description: >- Reserved but not active on Speak. Sending this field currently returns `400 unsupported_parameter`. temperature: type: number description: >- Reserved but not active on Speak. Sending this field currently returns `400 unsupported_parameter`. responses: '200': description: >- Audio bytes. Bytes are delivered incrementally by default; `stream: false` returns a complete buffered body. The `Content-Type` varies by `response_format`: `audio/wav` (wav), `audio/mpeg` (mp3), `audio/ogg` (opus), `audio/aac` (aac), `audio/flac` (flac), `audio/pcm` (pcm, raw/headerless), and `audio/basic` (g711_ulaw/g711_alaw, raw/headerless G.711 at 8 kHz mono). content: audio/wav: schema: type: string format: binary audio/mpeg: schema: type: string format: binary audio/ogg: schema: type: string format: binary audio/aac: schema: type: string format: binary audio/flac: schema: type: string format: binary audio/pcm: schema: type: string format: binary audio/basic: schema: type: string format: binary '401': $ref: '#/components/responses/Unauthorized' '402': $ref: '#/components/responses/PaymentRequired' '403': $ref: '#/components/responses/Forbidden' '409': description: >- A cloned voice that is `ready` but has not yet reached the render tier (`code: voice_propagating`). Honour `Retry-After` (60 s) and retry the same request; do not re-enroll. '429': $ref: '#/components/responses/RateLimited' components: responses: Unauthorized: description: 'Missing or invalid API key (`code: unauthorized`)' content: application/json: schema: $ref: '#/components/schemas/Error' PaymentRequired: description: >- Billing gate: org out of prepaid credit, per-key budget hit, or plan quota exhausted (`code: credit_exhausted | key_budget_exceeded | insufficient_quota`). Do not retry; add credit or raise the limit. A brand-new key may see this on its first call until the account is funded. content: application/json: schema: $ref: '#/components/schemas/Error' Forbidden: description: >- Key lacks the required scope or the origin is not allow-listed (`code: forbidden | origin_not_allowed`) content: application/json: schema: $ref: '#/components/schemas/Error' RateLimited: description: >- Too many requests or too many concurrent realtime sessions; see Retry-After header (`code: rate_limit_exceeded | concurrency_limit_exceeded | daily_cap_exceeded`) headers: Retry-After: schema: type: integer description: Seconds to wait. content: application/json: schema: $ref: '#/components/schemas/Error' schemas: Error: type: object description: >- OpenAI-compatible error envelope returned by the gateway data plane (401/402/403/429). Control-plane request/resource errors use Problem (application/problem+json) instead. required: - error properties: error: type: object required: - message properties: message: type: string description: Human-readable explanation. type: type: string description: Error category, e.g. rate_limit_error. code: $ref: '#/components/schemas/ErrorCode' param: type: string nullable: true description: Offending parameter when applicable, else null. ErrorCode: type: string description: >- Stable, machine-readable error code. Branch on this rather than the human `message`. enum: - invalid_request_error - invalid_session_label - unauthorized - forbidden - origin_not_allowed - credit_exhausted - key_budget_exceeded - insufficient_quota - rate_limit_exceeded - concurrency_limit_exceeded - daily_cap_exceeded securitySchemes: apiKey: type: http scheme: bearer description: 'Use `Authorization: Bearer pyai_live_...` (or `pyai_test_...`).' xApiKey: type: apiKey in: header name: x-api-key description: >- Header alias for bearer auth on HTTP endpoints. WebSocket auth uses the subprotocol pair `pyai.v1, pyai-key.`. ````