Overview

Model

higgs-tts-3

Speech endpoint (POST)

https://api.boson.ai/v1/audio/speech

Need a model that listens and responds across turns? Use Higgs Realtime. Higgs TTS 3 renders speech from text; it does not manage a conversation.

Features

Chat-native, low-latency streaming — hear audio within moments of sending text, either by streaming speech from a request or by sending text over a WebSocket as your LLM generates it. See Streaming TTS.
100 languages — single-digit WER/CER coverage. See Languages.
Instant voice cloning — zero-shot from a short reference clip and its transcript. See Voices.
Inline control tags — shape emotion, style, prosody, and sound effects with <|emotion:…|>, <|style:…|>, <|prosody:…|>, and <|sfx:…|>. See Tags.
Timestamps — get the time each token is spoken, mapped back to your input, with the audio or as it streams. See Timestamps.

Try it in the playground

The fastest way to hear the model is the playground. Pick a voice, paste text, and press play.

Generate speech with the API

You need a Boson API key stored in BOSON_API_KEY, and available credit — new accounts must claim their free trial credit before their first API call. Set the key in your shell for the current session:

export BOSON_API_KEY=bai-xxxx

A minimal request needs Authorization, model, and input. Everything else is optional.

curl https://api.boson.ai/v1/audio/speech \
  -H "Authorization: Bearer $BOSON_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "higgs-tts-3",
    "input": "Hello, this is a test."
  }' \
  --output out.mp3

import os
import requests

resp = requests.post(
    "https://api.boson.ai/v1/audio/speech",
    headers={"Authorization": f"Bearer {os.environ['BOSON_API_KEY']}"},
    json={
        "model": "higgs-tts-3",
        "input": "Hello, this is a test.",
    },
)
resp.raise_for_status()
with open("out.mp3", "wb") as f:
    f.write(resp.content)

import { writeFile } from "node:fs/promises";

const res = await fetch("https://api.boson.ai/v1/audio/speech", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.BOSON_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    model: "higgs-tts-3",
    input: "Hello, this is a test.",
  }),
});
await writeFile("out.mp3", Buffer.from(await res.arrayBuffer()));

Use a preset voice

Use voice to choose a preset speaker.

curl https://api.boson.ai/v1/audio/speech \
  -H "Authorization: Bearer $BOSON_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "higgs-tts-3",
    "input": "Hello, this is a test.",
    "voice": "jake"
  }' \
  --output out.mp3

import os
import requests

resp = requests.post(
    "https://api.boson.ai/v1/audio/speech",
    headers={"Authorization": f"Bearer {os.environ['BOSON_API_KEY']}"},
    json={
        "model": "higgs-tts-3",
        "input": "Hello, this is a test.",
        "voice": "jake",
    },
)
resp.raise_for_status()
with open("out.mp3", "wb") as f:
    f.write(resp.content)

import { writeFile } from "node:fs/promises";

const res = await fetch("https://api.boson.ai/v1/audio/speech", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.BOSON_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    model: "higgs-tts-3",
    input: "Hello, this is a test.",
    voice: "jake",
  }),
});
await writeFile("out.mp3", Buffer.from(await res.arrayBuffer()));

See Voices for more preset speakers and samples.

Use reference audio

Use ref_audio to clone a voice from a short reference clip. Passing the audio transcript through ref_text can often improve generated audio quality.

curl https://api.boson.ai/v1/audio/speech \
  -H "Authorization: Bearer $BOSON_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "higgs-tts-3",
    "input": "Hello, this is a test.",
    "ref_audio": "https://docs.boson.ai/public/audio/sample.mp3",
    "ref_text": "Same voice, same words, and uh, a completely different presence. I was built for chat native voice, real-time, expressive, and controllable."
  }' \
  --output out.mp3

import os
import requests

resp = requests.post(
    "https://api.boson.ai/v1/audio/speech",
    headers={"Authorization": f"Bearer {os.environ['BOSON_API_KEY']}"},
    json={
        "model": "higgs-tts-3",
        "input": "Hello, this is a test.",
        "ref_audio": "https://docs.boson.ai/public/audio/sample.mp3",
        "ref_text": "Same voice, same words, and uh, a completely different presence. I was built for chat native voice, real-time, expressive, and controllable.",
    },
)
resp.raise_for_status()
with open("out.mp3", "wb") as f:
    f.write(resp.content)

import { writeFile } from "node:fs/promises";

const res = await fetch("https://api.boson.ai/v1/audio/speech", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.BOSON_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    model: "higgs-tts-3",
    input: "Hello, this is a test.",
    ref_audio: "https://docs.boson.ai/public/audio/sample.mp3",
    ref_text:
      "Same voice, same words, and uh, a completely different presence. I was built for chat native voice, real-time, expressive, and controllable.",
  }),
});
await writeFile("out.mp3", Buffer.from(await res.arrayBuffer()));

To clone from a local file, either encode local file as base64 string or send as `multipart/form-data. Below code shows the latter.

curl https://api.boson.ai/v1/audio/speech \
  -H "Authorization: Bearer $BOSON_API_KEY" \
  -F model=higgs-tts-3 \
  -F input="Hello, this is a test." \
  -F [email protected] \
  -F ref_text="Transcript of the reference clip." \
  --output out.mp3

import os
import requests

with open("voice.wav", "rb") as ref_audio:
    resp = requests.post(
        "https://api.boson.ai/v1/audio/speech",
        headers={"Authorization": f"Bearer {os.environ['BOSON_API_KEY']}"},
        data={
            "model": "higgs-tts-3",
            "input": "Hello, this is a test.",
            "ref_text": "Transcript of the reference clip.",
        },
        files={"ref_audio": ref_audio},
    )

resp.raise_for_status()
with open("out.mp3", "wb") as f:
    f.write(resp.content)

import { readFile, writeFile } from "node:fs/promises";

const form = new FormData();
form.set("model", "higgs-tts-3");
form.set("input", "Hello, this is a test.");
form.set("ref_text", "Transcript of the reference clip.");
form.set("ref_audio", new Blob([await readFile("voice.wav")]), "voice.wav");

const res = await fetch("https://api.boson.ai/v1/audio/speech", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.BOSON_API_KEY}`,
  },
  body: form,
});
await writeFile("out.mp3", Buffer.from(await res.arrayBuffer()));

You must own the right to clone the voice.

See Voices for best practices and reusable custom voices.

Fine-grained control

Inline tags control emotion, style, prosody, and sound effects in the generated audio. Add them to input, and the model adjusts the surrounding speech. For example:

Sample input	Sample audio
`<\|emotion:enthusiasm\|>Welcome to the show! <\|prosody:pause\|>Let's get started!`	`voice: "jake"`

See Tags for the complete list and sample audio.

Text normalization

Normalization rewrites the input so the model speaks it the way a person would read it aloud, expanding numbers, dates, times, currency, units, URLs, email addresses, phone numbers, abbreviations, and symbols into spoken form. It is on by default and leaves inline tags and ordinary prose untouched. Set normalize: false to synthesize the text exactly as written.

Sample input	Sample audio
`Your appointment is on Thu, Mar 3rd at 8:05 AM. The total is $1,250.75, and the balance of $89.50 is due by 5 PM on 3/17. See https://docs.boson.ai/models/higgs-tts/overview or call us at (415) 555-0142.`

If language is not set, normalization infers the language from the text. If you know the language, set language to its ISO 639-3 code, such as eng or cmn, for the most reliable results.

API reference

Full request body:

{
  "model": "higgs-tts-3",
  "input": "Text to synthesize.",
  "voice": "default",
  "response_format": "mp3",
  "stream": false,

  "ref_audio": "base64 | data URI | URL",
  "ref_text": "Transcript of the reference audio.",

  "normalize": true,
  "language": null,
  "timestamps": false
}

See the API reference for field details and additional options. To stream the audio, or the text as well, see Streaming TTS.

Alternative ways to use the model

Beyond the hosted API, you can run the model yourself:

Hugging Face — open model weights at bosonai/higgs-tts-v3-4b.
SGLang — serve the model locally for high-throughput inference. See the Higgs TTS cookbook.

Get started

Account & billing

Higgs Realtime

Higgs TTS 3

Higgs Avatar

Help

Features

Try it in the playground

Generate speech with the API

Use a preset voice

Use reference audio

Fine-grained control

Text normalization

API reference

Alternative ways to use the model