# OpenAI GPT-4o Mini TTS (Text-to-Speech)

> OpenAI GPT-4o Mini TTS (Text-to-Speech) is a paid API for AI agents from openai.mm.family, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-02).

Converts text input into spoken audio using OpenAI's gpt-4o-mini-tts model, returning binary audio bytes in formats like MP3, with support for custom voice instructions and speed control.

## Facts

- Endpoint: POST https://openai.mm.family/x402/v1/models/gpt-4o-mini-tts/audio/speech?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/openai-gpt-4o-mini-tts-text-to-speech-db1bc07e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_117zI93TgP_oQkrcxvedV

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 openai-gpt-4o-mini-tts-text-to-speech-db1bc07e -d '<json body>'
```

Example prompt: Can you read this product announcement aloud using gpt-4o-mini-tts — use the 'alloy' voice, speak at 1.0x speed, and keep a professional tone: 'We're thrilled to introduce our new AI-powered assistant, available today'? Give me an mp3.

## When to prefer this

Choose this endpoint when you need cost-effective AI text-to-speech with instruction-following capability (e.g. controlling tone, emotion, or accent), and your text is under 4096 characters. Prefer gpt-4o-mini-tts over tts-1 or tts-1-hd when you want a modern, instruction-aware model at a lower price point. Prefer this over gpt-4o-mini-tts alternatives when you need x402/USDC micropayment billing with no subscription required.

## Known failure modes

- Input text exceeds 4096 character limit — request rejected
- Invalid voice name provided — API error
- Unsupported response_format value — schema validation error
- Payment failure or insufficient USDC balance — 402 payment required error
- Empty or missing input field — bad request error
- Network timeout on audio generation — connection error

## How this service works

gpt-4o-mini-tts: OpenAI GPT 4o Mini TTS text to speech, paid per call in USDC. OpenAI list $12 per 1M audio tokens (quoted at 4 per character) plus $0.6 per 1M text tokens, plus $0.0005 (Base) or $0.0005 (Solana) per call; up to 4096 characters; accepts instructions. Returns the audio bytes (mp3 by default). Rates: https://openai.mm.family/x402/pricing

## Output

Returns binary audio bytes (default: MP3, audio/mpeg) of the synthesized speech. Supports formats including mp3, opus, aac, flac, wav, and pcm. The audio represents the input text spoken in the selected voice, at the specified speed, and optionally shaped by custom instructions.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "input": {
   "type": "string"
  },
  "model": {
   "enum": [
    "gpt-4o-mini-tts"
   ],
   "type": "string"
  },
  "speed": {
   "type": "number"
  },
  "voice": {
   "type": "string"
  },
  "instructions": {
   "type": "string"
  },
  "response_format": {
   "enum": [
    "mp3",
    "opus",
    "aac",
    "flac",
    "wav",
    "pcm"
   ],
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "body": "binary audio bytes (mp3 by default)",
  "content_type": "audio/mpeg"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/openai-gpt-4o-mini-tts-text-to-speech-db1bc07e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from openai.mm.family](https://www.zero.xyz/host/openai.mm.family/llms.txt)