Build a Voice Cloning Demo App

Description and use

This article walks through a complete end-to-end voice cloning demo using the ElevenLabs API: upload a short WAV sample, create a cloned voice, and synthesize text on demand via a Python script and optionally a Flask web service

Problem

How to create a complete, end-to-end voice cloning demo that lets users upload a short sample, generate a cloned voice, and synthesize any text on demand using the ElevenLabs API.

Outcome

A complete end-to-end voice cloning demo: upload a ~30-second WAV sample, create a cloned voice via ElevenLabs API, then synthesize arbitrary text on demand using a Python script and optionally a Flask web service.

Workflow

• Get an ElevenLabs API key from https://try.elevenlabs.io/kr07zfuqn1bp and store it as ELEVENLABS_API_KEY environment variable
• Upload a short voice sample (≈30 seconds, WAV 16-bit 44.1 kHz) via multipart/form-data POST to /v1/voices/add with name=MyDemoVoice
• Save the returned voice_id for later use
• Run a Python script (synth_demo.py) that POSTs to /text-to-speech/{voice_id} with text, model_id=eleven_monolingual_v1, stability=0.75, similarity_boost=0.85, and writes the streamed WAV bytes to output.wav
• Optionally wrap the synthesis logic in a Flask app exposing a /speak POST endpoint that accepts JSON text and returns synthesized audio or JSON response

Evidence

Modern text-to-speech (TTS) platforms can take a few minutes of recorded audio and generate a synthetic voice that sounds almost indistinguishable from the real thing.

Source

In this post we’ll walk through a complete, end-to-end demo that lets you upload a short sample, generate a cloned voice, and then synthesize any text on demand. We’ll use the ElevenLabs API, which is currently one of the most developer-friendly services for high-quality voice cloning.

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The ElevenLabs free tier gives you 10 k characters per month—perfect for experimenting.

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The file must be a WAV (16-bit, 44.1 kHz) for best results.

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curl -X POST "https://api.elevenlabs.io/v1/voices/add" -H "xi-api-key: $ELEVENLABS_API_KEY" -F "name=MyDemoVoice" -F "files[]=@/path/to/voice_sample.wav"

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POST /text-to-speech/{voice_id} with your text. Passes optional voice_settings to tweak stability (smoothness) and similarity boost (how close it stays to the original sample). Streams the returned WAV data directly to output.wav.

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If you want to expose the demo as a simple API endpoint, Flask makes it a breeze:

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