# x402engine Voxtral Mini TTS via OpenRouter

> x402engine Voxtral Mini TTS via OpenRouter is a paid API for AI agents from x402engine.app, paid per call via x402, $0.06/call, status unknown (last checked 2026-10-16).

Converts up to 2000 bytes of text into MP3 audio using Voxtral Mini, offering 30 preset voices across English, British, and French accents with emotional tones

## Facts

- Endpoint: POST https://x402engine.app/api/tts/openrouter?utm_source=zero.xyz
- Price: $0.06/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402engine-voxtral-mini-tts-via-openrouter-7ac33e2c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_3cMBhNTSzkFd0WT2iUaC7

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability x402engine-voxtral-mini-tts-via-openrouter-7ac33e2c -d '<json body>'
```

Example prompt: Turn this text into spoken audio using the en_paul_excited voice: 'Welcome to our product launch — we're thrilled to have you here!'

## When to prefer this

Choose this endpoint when you need pay-per-call TTS with no subscription, want a specific emotional tone or accent (30 presets across American, British, and French voices), and need MP3 output in a single low-latency call. Ideal for agents that generate dynamic audio on demand without managing API keys for a dedicated TTS provider.

## Known failure modes

- Text exceeds 2000 UTF-8 bytes — request rejected with validation error
- Invalid or unsupported voice enum value — returns error
- Empty text field — returns validation error
- Payment failure (HTTP 402) if USDC micropayment is not completed
- Network timeout if OpenRouter backend is slow or unavailable

## How this service works

x402engine — Voxtral Mini TTS through OpenRouter; 30 voices, MP3 audio, up to 2000 UTF-8 bytes of text

## Output

A JSON object containing a base64-encoded MP3 audio string and the format field ('mp3'). The agent decodes the base64 string to obtain playable or saveable audio bytes.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "bodyType",
    "body",
    "method"
   ],
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "text"
     ],
     "properties": {
      "text": {
       "type": "string",
       "example": "Hello world",
       "description": "Non-empty text, at most 2000 UTF-8 bytes"
      },
      "voice": {
       "enum": [
        "en_paul_sad",
        "en_paul_neutral",
        "en_paul_happy",
        "en_paul_frustrated",
        "en_paul_excited",
        "en_paul_confident",
        "en_paul_cheerful",
        "en_paul_angry",
        "gb_oliver_neutral",
        "gb_oliver_sad",
        "gb_oliver_excited",
        "gb_oliver_curious",
        "gb_oliver_confident",
        "gb_oliver_cheerful",
        "gb_oliver_angry",
        "gb_jane_sarcasm",
        "gb_jane_confused",
        "gb_jane_shameful",
        "gb_jane_sad",
        "gb_jane_neutral",
        "gb_jane_jealousy",
        "gb_jane_frustrated",
        "gb_jane_curious",
        "gb_jane_confident",
        "fr_marie_sad",
        "fr_marie_neutral",
        "fr_marie_happy",
        "fr_marie_excited",
        "fr_marie_curious",
        "fr_marie_angry"
       ],
       "type": "string",
       "default": "en_paul_neutral",
       "description": "Voxtral preset voice"
      },
      "format": {
       "enum": [
        "mp3"
       ],
       "type": "string",
       "default": "mp3",
       "description": "Fixed MP3 output"
      }
     },
     "additionalProperties": false
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "required": [
      "audio",
      "format"
     ],
     "properties": {
      "audio": {
       "type": "string",
       "description": "Base64-encoded audio bytes. Decode to save or play the audio."
      },
      "format": {
       "type": "string",
       "description": "The audio encoding selected for this request."
      
… (truncated)
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "audio": "<base64-encoded audio>",
  "format": "mp3"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402engine-voxtral-mini-tts-via-openrouter-7ac33e2c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402engine.app](https://www.zero.xyz/host/x402engine.app/llms.txt)