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AI Voice — OpenAI: GPT-4o Audio

Commercial use OK 380+ models No watermark No sign-up needed
Model:
+ GPT-5, Claude, Gemini
TTS engine Premium
OpenAI: GPT-4o Audio — OpenAI: GPT-4o Audio is an AI model by OpenAI on Free.ai. It supports up to 128,000 tokens of context. Costs approximately 4,781 tokens per message. Try OpenAI: GPT-4o Audio instantly — no sign up needed. Compare it side-by-side with other…
0 characters ~0 tokens
Cost scales with character count
Generating speech...

What does OpenAI: GPT-4o Audio sound like?

OpenAI: GPT-4o Audio is an AI model by OpenAI on Free.ai. It supports up to 128,000 tokens of context. Costs approximately 4,781 tokens per message. Try OpenAI: GPT-4o Audio instantly — no sign up needed. Compare it side-by-side with other models.

Try the box above with: Hello, my name is Sam, and I am reading this sample to demonstrate the voice. — that is the canonical TTS demo phrase.

When to use OpenAI: GPT-4o Audio

Audiobooks

Long-form narration with consistent tone. Paste a chapter at a time, download as WAV or MP3, and stitch externally.

Podcast intros

Short opening bumpers and ad-reads. Adjust speed for energy, format-switch to MP3 for smaller files.

IVR + voicemail

Phone-system prompts. Studio-quality output without a booking, recording, or NDAs with voice talent.

Accessibility

Add audio alongside written content for low-vision and dyslexic readers. Drop-in on any page.

Sample phrases

"Welcome to the show, today we are exploring the future of AI."
"Your package has arrived. Please retrieve it from the front desk."
"Once upon a time, in a quiet village far away, lived a curious child."
"Press one for sales, two for support, or stay on the line for an agent."
"Breaking news: scientists have discovered a new species of deep-sea fish."
"Thank you for choosing us. We appreciate your business and look forward to serving you again."

Pricing

Premium TTS. Cost scales with character count — typically ~30 tokens per character. $1 buys 750,000 tokens; a $5 token pack covers tens of thousands of characters. Free signups get 10,000 tokens to try.

Full model reference → · See all TTS voices → · Compare 2 voices side-by-side →

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OpenAI: GPT-4o Audio is an AI model by OpenAI on Free.ai. It supports up to 128,000 tokens of context. Costs approximately 4,781 tokens per message. Try Op…

Mokhoa oa ho sebelisa AI Voice — OpenAI: GPT-4o Audio

1
Ke eng eo u e kentseng?

Tlatsa mongolo, kenya faele, kapa hlalosa seo u se batlang. Ha ho hlokahale ak'haonte.

2
Tobetsa ho theha

AI ea rona e sebetsana le kopo ea hau ka metsotsoana ka ho sebelisa li-models tse ntlehali tsa open-source.

3
Tlosa & & arolelana

Kopitsa, kenya kapa arolelana litlamorao tsa hau. Haholo-holo bakeng sa ho sebelisana le batho ba bang le ho rekisa.

Use this tool via API

Automate this tool from your own code. OpenAI-compatible REST endpoint, Bearer-token auth, no extra SDK required. Token costs match the web interface.

API Documentation Get API Key 
curl -X POST https://api.free.ai/v1/tts/ \
  -H "Authorization: Bearer sk-free-..." \
  -H "Content-Type: application/json" \
  -d '{"text": "Hello from Free.ai", "voice": "af_heart", "model": "kokoro"}'

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AI Voice — OpenAI: GPT-4o Audio — FAQ

OpenAI: GPT-4o Audio supports a wide range of languages. The exact list depends on the engine; the form on this page accepts any text and the engine will render in its supported languages. See /voice/ for the full multi-engine picker if you need a specific language.

Most engines render neutral-American English by default and a region-appropriate accent for non-English languages. Premium engines may expose accent variants — paste a sample to compare.

SSML support varies by engine. Pause, prosody, and emphasis tags are honored on most premium engines and on a few self-hosted ones. Plain text always works — no markup required.

Streaming TTS is available on premium engines via the /v1/tts/ API endpoint with stream=true. The web UI on this page returns the full clip once rendering finishes.

OpenAI: GPT-4o Audio is a premium TTS engine. Cost scales with character count — typically ~30 tokens per character. $1 buys 750,000 tokens, so a $5 pack covers tens of thousands of characters.

Up to 5,000 characters per request on the web UI. For longer pieces (audiobooks, full chapters), use /voice/audiobook/ which chunks and stitches automatically, or call the API in a loop.

Yes — POST a list of strings to /v1/tts/batch/, or use the workspace UI at /workspace/ to chain TTS into a longer pipeline (e.g., translate → speak → stitch).

Yes — POST text to /v1/tts/ with model="OpenAI: GPT-4o Audio" (or the slug on this page). Returns WAV or MP3. See /api/ for full reference + SDK snippets.

This page is text-to-speech, not voice cloning — the voice is the engine's default. For voice cloning (uploading a reference audio), see /voice/clone/, which requires you to either own the voice rights or have explicit written consent.

Self-hosted engines run on Free.ai-owned GPUs; nothing leaves our servers. Premium engines pass text to upstream model providers under our DPA. We do not train on your inputs and do not sell data.

Yes — Free.ai grants commercial use of generated audio. The engine's underlying license (Apache 2.0, MIT, or vendor terms) is shown above and on the model reference page; in practice this means voiceovers, ads, podcasts, and apps are all in-scope.

Yes — failed jobs auto-refund to the source (daily pool or paid tokens). If a refund does not show up the same day, email contact@free.ai.

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