Grok TTS API

Introduction

What it returns

One audio file per task — MP3 at 24 kHz, 128 kbps, mono unless you ask otherwise. There are no word timings or subtitles in the result.

Choosing a voice

voice_id takes one of 71 preset voices and defaults to eve. Eve, Ara, Leo, Rex and Sal speak every supported language. The other 66 are each tuned for one language — Mandarin, Russian, Italian, Hindi, French, Spanish, Danish, Vietnamese, English, Swedish, Finnish, Turkish, Japanese, Korean, Portuguese, Dutch, Polish, Thai, Arabic or German — and read best in it. The form lists every voice with its name, gender and language.

Directing the delivery with tags

Write the performance into text. Instant tags make one sound at that point: [pause], [long-pause], [hum-tune], [laugh], [chuckle], [giggle], [cry], [tsk], [tongue-click], [lip-smack], [breath], [inhale], [exhale], [sigh]. Wrapping tags change the words inside them: <soft>, <whisper>, <loud>, <build-intensity>, <decrease-intensity>, <higher-pitch>, <lower-pitch>, <slow>, <fast>, <sing-song>, <singing>, <laugh-speak>, <emphasis>. The tags we tried were acted out and never read out as words.

Speed, language and format

speed runs from 0.7 to 1.5. language is detected when left on auto; set it when a short or mixed script comes out in the wrong one. output_format is mp3 by default; wav suits editing, and pcm, mulaw and alaw are header-less streams for phone systems — pair them with sample_rate 8000. bitrate only affects MP3.

Request parameters

Pricing

Prices are in credits, the same credits you use on the website (1 credit = $0.01). The hold is taken when the task is accepted and settled to the actual charge when it finishes; failed tasks are refunded.

Each task is rounded up to whole credits, so one run at the lowest tier costs 3 credits per 1,000 characters ($0.03).

For an exact number before you run, send the same body to POST /jobs/quote.

API quick start

Call the Grok TTS API in three steps

1. Create an API key. Sign in to PopNow and create a key in the API console. Keys start with sk-popnow- and use the same credits as the website.
2. Send the request. POST /jobs/createTask with model xai/grok-tts/text-to-speech and an input object that follows the parameter table. The response returns a task ID straight away.
3. Get the result. Poll GET /jobs/recordInfo with the task ID, or pass a callBackUrl and we post the result to it. Download the output links when the task succeeds.

# 1. Create the task. Keep the Idempotency-Key if you retry after a network error.
export IDEMPOTENCY_KEY="$(uuidgen)"
curl -X POST https://api.popnow.ai/api/v1/jobs/createTask \
  -H "Authorization: Bearer $POPNOW_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $IDEMPOTENCY_KEY" \
  -d '{
  "model": "xai/grok-tts/text-to-speech",
  "input": {
    "text": "Welcome back. Your files finished rendering a minute ago and are ready to download.",
    "voice_id": "eve",
    "language": "auto"
  }
}'

# 2. Copy data.taskId from the response, then poll until state is succeeded, failed, canceled or expired.
TASK_ID="TASK_ID_FROM_RESPONSE"
curl "https://api.popnow.ai/api/v1/jobs/recordInfo?taskId=$TASK_ID" \
  -H "Authorization: Bearer $POPNOW_API_KEY"

Replace the prompt and any links with your own. The API tab has the response, polling and callback reference.

Grok TTS API questions

All Grok models

Gemini 3.8 Flash TTS gives a more acted read with two voices in one file. Grok is the one for long scripts in one request.

• Grok STT APITranscripts with word timings in 25 languagesFrom 0.01 credits per second
• Grok TTS API71 voices across 20 languages with speech tagsFrom 3 credits per 1,000 characters

Other audio APIs

• Gemini 3.8 Flash TTS APIExpressive speech that acts out cues like [laughing]From 0.05 credits per second
• MiniMax Speech 2.8 HD APIHigh-fidelity speech in 400+ voices with emotion controlFrom 18 credits per 1,000 characters
• Gemini 3.8 Flash-Lite TTS APIFast, lightweight speech in 30 voicesFrom 0.03 credits per second
• Seed Speech 2.0 API41 voices with tone set in plain languageFrom 11 credits per 1,000 characters
• MiniMax Speech 2.8 Turbo APIFast speech in 400+ voices with emotion controlFrom 11 credits per 1,000 characters
• Qwen3 TTS APIOpen-source speech with tone and pace set in plain wordsFrom 11 credits per 1,000 characters

More about Grok TTS

Try it

Grok TTS AI Voice Generator onlineCreate audio with Grok TTS in PopNow

Docs

Grok TTS model ID and input schema in the API docsPopNow API quickstart: your first request in five minutesWebhooks: get Grok TTS results without polling