AI speech synthesis free to try, no sign-up

Speech synthesis is the use of software to turn written text into spoken audio. It is also called text to speech (TTS) or voice synthesis. Modern systems use AI models trained on recorded speech, so they sound far closer to a person than the robotic voices of older software.

A phone agent reading back your appointment time, a navigation app announcing the next turn, and a screen reader speaking a web page all use speech synthesis. So does the demo at the top of this page, which reads the text you type into it.

The demo on this page is free, with no sign-up. To use the API in your own app, create an account: the Free plan includes 20,000 credits a month, and paid plans add more.

Speech synthesis turns text into spoken audio. Speech recognition turns spoken audio into text. A voice agent chains them with a language model: recognition hears the caller, the model writes the reply, and synthesis speaks it. Cartesia makes Sonic for text to speech and Ink for speech to text.

An AI model reads the text and predicts how it should sound: how each word is pronounced, the rhythm of the sentence, and where the emphasis falls. It then generates the audio. Cartesia's models stream that audio as they generate it, so playback starts before the sentence is finished.

No. The browser's window.speechSynthesis speaks text with the voices the listener's browser and operating system provide, so the voice changes from one device to the next. Cartesia is a hosted API that returns generated audio to your application, in the same voice everywhere. For browser-only playback without an API key, see the JavaScript text-to-speech tutorial.

Create an API key, keep it on your backend, and send text with a voice ID; the API returns audio. The Python text-to-speech guide shows how to generate and save a WAV file in a few lines. For a phone or voice agent, stream the audio over a WebSocket, or let Cartesia Managed Agents run the agent and its calls.

Cartesia's voices speak 40+ languages from one model, with regional accents such as American, British, and Australian English, Canadian French, and Mexican Spanish. The languages page has samples in each language.

Yes. Over a WebSocket or server-sent events, Cartesia sends audio in chunks as it is generated, so your app can start playback before the whole clip is ready. The streaming API reference shows the response format.

Yes. You can set speaking speed and volume and choose from 60+ emotions to change the delivery. The voice controls guide lists the options for each model.

Voice cloning creates a reusable voice from recordings of a speaker. Speech synthesis then uses that voice, or any stock voice, to read new text. The voice cloning page covers recording requirements.