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fastapi.online Voice Clone (Speech Synthesis from Reference Audio)
x402
fastapi.online Voice Clone (Speech Synthesis from Reference Audio) is a paid API for AI agents from api.fastapi.online, paid per call via x402, $0.05/call, status down (last checked 2026-09-15).
Clones a speaker's voice from a short reference audio clip and synthesizes new speech from provided text, returning a WAV audio file.
Price / call$0.05
Success—
StatusDown
How this service works
Self-hosted AI API gateway. Expensive endpoints require an x402 micropayment (USDC on Base) before executing.
Output
A JSON object containing an 'audio_base64' field with the base64-encoded WAV audio of the synthesized speech in the cloned voice, and a 'format' field confirming the output is WAV.
Example use cases
Personalized voicemail greeting generator
“I have a 5-second WAV recording of my voice saying 'Hey, this is Jordan, leave a message.' — can you clone my voice and make it say 'Hi, you've reached Jordan's phone, I'm unavailable right now, please leave your name and number after the beep' instead?”
Audiobook narration in author's voice
“I have a base64-encoded MP3 of the author reading a paragraph — the transcript is 'This is the voice of the narrator for this story.' — can you clone that voice and generate audio of it reading: 'Chapter one. The morning sun rose slowly over the quiet valley, casting long golden shadows across the dew-covered grass.'”
Multilingual content in original speaker's voice
“I've got a short WAV clip of our CEO saying 'Hello and welcome to the company' — use that to clone their voice and generate audio of them saying 'Thank you for joining us today for this important announcement about our new product launch.'”
Technical details
Endpoint
POSThttps://api.fastapi.online/voice-cloneWhen to prefer
Choose this endpoint when you need to synthesize speech that mimics a specific person's voice given only a short reference recording — ideal for personalized audio generation, voice preservation, or custom narration. Prefer this over generic TTS endpoints when voice identity matters and you have a reference sample. Best for single-call, pay-per-use scenarios with no signup overhead.
Side effects
- Reference audio too short or low quality — cloning fails or produces distorted output
- Base64 encoding of audio is malformed — returns a 400 or processing error
- Text input exceeds 5000 characters — rejected by schema validation
- Reference transcript does not match the reference audio — reduced cloning accuracy
- Audio format unsupported (non-WAV/MP3) — processing error
- Payment of $0.05 USDC not completed — 402 Payment Required response
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"format": "wav",
"audio_base64": "<wav>"
}
}Tags
x402
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