Text-to-speech (OpenAI-compatible /v1/audio/speech)
Text-to-speech (OpenAI-compatible /v1/audio/speech). 4,358 voices across 9 providers (KokoroTTS, AWS Polly, Azure, MiniMax, more — free catalog at GET /v1/audio/voices). Returns mp3. Up to 3000 chars. $0.000006 USDC per character (Telnyx list rate, zero margin): pay per character via the upto scheme (min $0.002 network settlement floor, so ≤333-char calls settle at $0.002), or flat $0.018 exact.
Answeringour last check, 2026-10-18
1 of 1checks answered this week
316 msmedian answer time
$0.018listed price per call
$0.018price it asked us
Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.
Endpoint
POST https://x402.telnyx.com/v1/audio/speech
| Category | Image and media |
|---|---|
| Provider host | x402.telnyx.com |
| Networks | eip155:8453 |
| Payment schemes | exact, upto |
| Self-reported calls, 30 days | 18 from 2 payers (the provider's figure, not ours) |
Our checks, last 30 days
| Day | Result | HTTP | Asked | Time |
|---|---|---|---|---|
| 2026-10-18 | valid payment request | 402 | $0.018 | 316 ms |
Example input (from the provider)
{
"body": {
"input": "Hello from the Telnyx x402 gateway.",
"model": "tts-1",
"voice": "alloy"
},
"bodyType": "json",
"method": "POST",
"type": "http"
}
Promised output schema (from the provider)
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"body": {
"properties": {
"input": {
"description": "Text to synthesize (max 3000 characters).",
"maxLength": 3000,
"minLength": 1,
"type": "string"
},
"model": {
"description": "Accepted for OpenAI SDK compatibility; the voice id selects the engine.",
"type": "string"
},
"response_format": {
"enum": [
"mp3"
],
"type": "string"
},
"voice": {
"description": "OpenAI voice name (alloy, echo, fable, onyx, nova, shimmer, \u2026) or Telnyx voice id (Provider.Model.VoiceId). Full catalog: GET /v1/audio/voices.",
"type": "string"
}
},
"required": [
"input",
"voice"
],
"type": "object"
},
"bodyType": {
"enum": [
"json",
"form-data",
"text"
],
"type": "string"
},
"method": {
"enum": [
"POST"
],
"type": "string"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method",
"bodyType",
"body"
],
"type": "object"
},
"output": {
"properties": {
"example": {
"type": "object"
},
"type": {
"type": "string"
}
},
"required": [
"type"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}