Audio

Zabio transcribes audio through POST /v1/audio/transcriptions and turns text into speech through POST /v1/audio/speech, in the shape OpenAI’s SDKs already send. Change base_url and your key, keep the rest.

For the exact shape of every request and response, with curl, Python and Node examples, see the API reference. Audio inside a chat request (an input_audio part the model listens to and answers in text) is on the Chat completions page.

Transcription

Send an audio file and get its text back. The key needs the chat scope (keys have it by default).

curl https://api.zabio.ai/v1/audio/transcriptions \
  -H "Authorization: Bearer insert your zabio.ai key here" \
  -F file=@meeting.mp3 \
  -F model=auto

{
  "text": "Good morning, let us start with the numbers.",
  "usage": {"type": "duration", "seconds": 20.4},
  "zabio": {"call_id": "call_...", "vendor": "deepinfra", "model_served": "voxtral-mini-3b-2507", "cost_micros": 357, "units": {"kind": "audio_second", "seconds": 20.4, "estimated": false}}
}

Models

Model	Maker	Price per minute	Formats	Notes
gpt-transcribe	OpenAI	0.0045	json, text; streams	OpenAI’s recommended model; takes several expected languages
whisper-1	OpenAI	0.006	json, text, verbose_json, srt, vtt; word timestamps	retires on 2027-02-26 (OpenAI’s date)
gpt-4o-transcribe, gpt-4o-mini-transcribe, gpt-4o-transcribe-diarize	OpenAI	billed in audio tokens (2.50 and 1.25 per million; about 0.006 and 0.003 per minute, OpenAI’s estimate)	json, text	retire on 2027-02-26 (OpenAI’s date)
whisper-large-v3	OpenAI, served by Together AI	0.0015	json, text, verbose_json, srt, vtt; word timestamps	up to 4 hours of audio
voxtral-mini-3b-2507, voxtral-small-24b-2507	Mistral AI, served by DeepInfra	0.001 and 0.003	json, text, verbose_json	English, Spanish, French, Portuguese, Hindi, German, Dutch and Italian; up to 30 minutes
gemini-3.5-transcribe	Google	billed in audio tokens (2.00 per million; about 0.003 per minute, Google’s estimate at 25 tokens per second) plus 12.00 per million output tokens	json, text, verbose_json, srt, vtt; word timestamps	85 or more locales; up to 30 minutes; a prompt becomes custom vocabulary when no timestamps are asked
scribe-v2	ElevenLabs	0.0037 (0.22 per hour)	json, text, verbose_json, srt, vtt; word timestamps	90 or more languages; up to 10 hours
nova-3, nova-3-multilingual	Deepgram	0.0043 and 0.0052	json, text, verbose_json, srt, vtt; word timestamps	about 60 languages, or code-switching across about 50 with the multilingual model; billed per second; prompt and temperature are not sent

Prices are the provider’s list prices in USD; the plan fee applies on top (see Billing). GET /v1/models lists every transcription model with zabio.kind: "transcription", its unit and its formats, and the models page shows where each one is processed.

auto

model: auto picks the cheapest transcription model able to do what your request asks: the language you name, the timestamps and the format. There is no quality bar yet, so auto, auto/cheap, auto/balanced and auto/best all pick the same model on this endpoint. If the chosen model fails, Zabio tries the next one at the same vendor, and at other vendors when the key’s fallback setting allows it. An auto call pays the price of automatic model choice (at most 0.00025 USD) like any other auto call.

Request

Multipart form data, as OpenAI.

Field	Notes
file	required; mp3, mp4, mpeg, mpga, m4a, wav, webm, flac or ogg; 25 MB at most
model	a transcription model or auto (the default when absent)
language	ISO 639-1 code of the audio; detected when absent
languages	several expected languages, for the models that take them (gpt-transcribe); the first is sent to the others
prompt	context for the model: names, spelling, style
response_format	json (default), text, verbose_json, srt or vtt. Zabio renders srt and vtt from the model’s segment timestamps, so a model that returns no segments cannot serve them (400 unsupported_value)
timestamp_granularities	segment, word; with verbose_json
stream	true streams transcript.text.delta and transcript.text.done events as OpenAI does, with json format. A model that does not stream answers with the whole text in one done event at the end
temperature	0 to 1

Response

json returns text, the detected language where the model reports it, usage and the zabio object. verbose_json adds task, duration, segments and, when asked, words. text, srt and vtt return the file as text/plain.

The zabio object carries call_id, vendor, model_served, cost_micros (what the call cost you, fee included) and units: the seconds of audio billed, and estimated: true when the vendor reported no duration and Zabio read it from the file’s header.

What is billed

A minute of audio at the model’s price, plus the plan fee. The vendor’s own count of seconds or tokens is what Zabio bills; when a vendor reports none, Zabio reads the length from the file’s header, rounded up to the second, and marks it estimated. Models billed in audio tokens are billed on the tokens the vendor reports. A call that fails at the vendor is not billed. Your own OpenAI, Google, Together AI or DeepInfra key serves your named calls at no charge from Zabio (ElevenLabs and Deepgram own keys are not accepted yet); auto always runs on Zabio’s keys and needs credit.

What is stored

The audio file is sent to the vendor and dropped when the call ends: never written to a database, never logged. Zabio keeps the call’s metadata (model, vendor, seconds, cost) as for any call. If the key has body logging on, the transcript text and a reference to the media (type, size, seconds) are stored encrypted under your organization’s retention, never the audio. See Privacy.

Limits and errors

The key’s requests per minute limit applies (the token limit does not count audio). Spend limits, member quotas and the balance apply as on every call. A file above the cap returns 413 media_too_large; a file that is not audio returns 400 unsupported_format; a model named on this endpoint that is not a transcription model returns 400 unsupported_for_model. See Errors.

Python

from openai import OpenAI

client = OpenAI(base_url="https://api.zabio.ai/v1", api_key="insert your zabio.ai key here")
with open("meeting.mp3", "rb") as f:
    res = client.audio.transcriptions.create(model="auto", file=f, response_format="json")
print(res.text, res.model_extra["zabio"]["cost_micros"])

Speech

Send text and get audio back. The key needs the chat scope. The voices are AI-generated: tell your own users so where you play them, as the vendors’ terms require.

curl https://api.zabio.ai/v1/audio/speech \
  -H "Authorization: Bearer insert your zabio.ai key here" \
  -H "Content-Type: application/json" \
  -d '{"model": "auto", "input": "Good morning, let us start with the numbers.", "response_format": "mp3"}' \
  --output morning.mp3

The answer is the audio itself, sent in chunks as the model produces it, with the right Content-Type. Because the body is audio, the zabio fields come as response headers:

Content-Type: audio/mpeg
x-zabio-call-id: call_...
x-zabio-vendor: together
x-zabio-model-served: kokoro-82m
x-zabio-cost-micros: 189
x-zabio-units: character=45

Models

Model	Maker	Price	Formats	Voices	Notes
kokoro-82m	Hexgrad, served by Together AI	4.00 per million characters	mp3, wav, pcm	54, such as af_heart, am_adam, bf_emma; the prefix names the language and gender	the cheapest mp3; eight languages
aura-2	Deepgram	30.00 per million characters	mp3, opus, flac, wav, pcm	the Aura-2 voices, aura-2-thalia-en, aura-2-sirio-es and the rest, in English, Spanish, Dutch, French, German, Italian and Japanese	2,000 characters at most per request
eleven-v4, eleven-v4-turbo	ElevenLabs	80.00 and 40.00 per million characters	mp3, opus, wav, pcm	ElevenLabs’ default library, by voice id (JBFqnCBsd6RMkjVDRZzb and 18 more; see GET /v1/models)	90 or more languages; eleven-v4 takes 10,000 characters at most, which the endpoint’s own cap of 4,096 already keeps
gemini-3.8-flash-tts, gemini-3.8-flash-lite-tts	Google	billed in tokens: text in at 0.50 per million, audio out at 9.00 and 6.00 per million (about 0.00225 and 0.0015 per 10 seconds of audio, Google’s estimate at 25 tokens per second); these prices double on 2027-01-01, as Google’s page states	wav, pcm	30 prebuilt voices, Kore, Puck, Zephyr and the rest	over 130 languages, detected; instructions becomes the style
gpt-4o-mini-tts	OpenAI	billed in tokens: text in at 0.60, audio out at 12.00 per million	mp3, opus, aac, flac, wav, pcm	marin, cedar, alloy, ash, ballad, coral, echo, fable, nova, onyx, sage, shimmer, verse	takes instructions; by name only, shuts down on 2027-01-06 (OpenAI’s date)
tts-1, tts-1-hd	OpenAI	15.00 and 30.00 per million characters	mp3, opus, aac, flac, wav, pcm	alloy, ash, coral, echo, fable, onyx, nova, sage, shimmer	by name only, shut down on 2027-01-06 (OpenAI’s date)

Prices are the provider’s list prices in USD; the plan fee applies on top (see Billing). GET /v1/models lists every speech model with zabio.kind: "speech", its unit, its formats and its voices under zabio.media, and the models page shows where each one is processed.

Nothing is transcoded: each model returns the formats its vendor produces, so a request for aac or flac is served by Deepgram or OpenAI, and one for wav or pcm by any of them. pcm is raw 16-bit little-endian samples at 24 kHz with no header, on every model. opus comes in an Ogg container; the Content-Type is the vendor’s (audio/opus from OpenAI and ElevenLabs, audio/ogg from Deepgram).

auto

model: auto picks the cheapest speech model that offers the format you ask for and, if you name one, the voice; without a voice, each model speaks with its default (the first in its list). There is no quality bar yet, so auto, auto/cheap, auto/balanced and auto/best all pick the same model on this endpoint. If the chosen model fails before the first byte, Zabio tries the next one at the same vendor, and at other vendors when the key’s fallback setting allows it. An auto call pays the price of automatic model choice (at most 0.00025 USD) like any other auto call. The three OpenAI models are never picked by auto, since they shut down in January.

Request

JSON, as OpenAI.

Field	Notes
input	required; the text to speak, 4,096 characters at most
model	a speech model or auto (the default when absent)
voice	a voice the model lists; the model’s default when absent. A voice the model does not have returns 400 unsupported_value
response_format	mp3 (default), opus, aac, flac, wav or pcm. A format the model does not produce returns 400 unsupported_value
speed	0.25 to 4; the model’s default when absent. Models without a speed setting ignore it
instructions	style guidance for the models that take it (gpt-4o-mini-tts, the Gemini models); the others ignore it; 4,096 characters at most
stream_format	audio (the default). sse is not available through Zabio and returns 400 unsupported_value

Response

The audio, chunked, with Content-Type set to what the model returned. The headers carry what the zabio object carries elsewhere: x-zabio-call-id, x-zabio-vendor, x-zabio-model-served, x-zabio-cost-micros (what the call cost you, fee included) and x-zabio-units (character=312 on a model billed per character; text_input_token=80, audio_output_token=1250 on one billed in tokens).

What is billed

The characters of your input at the model’s price per million characters, plus the plan fee; or, on the Gemini and gpt-4o-mini-tts models, the text input and audio output tokens the vendor reports. A character is a Unicode code point. Where a vendor reports its own count of characters (Deepgram), that count is billed. A call that fails at the vendor before the first byte is not billed; a stream that breaks after the first byte is not billed either. Your own OpenAI, Google or Together AI key serves your named calls at no charge from Zabio (ElevenLabs and Deepgram own keys are not accepted yet); auto always runs on Zabio’s keys and needs credit.

What is stored

The audio is streamed to you and kept nowhere: never written to a database, never logged. Zabio keeps the call’s metadata (model, vendor, characters or tokens, cost) as for any call. If the key has body logging on, the input text and a reference to the media (type, bytes, characters) are stored encrypted under your organization’s retention, never the audio. See Privacy.

Limits and errors

The key’s requests per minute limit applies (the token limit does not count characters). Spend limits, member quotas and the balance apply as on every call. An input above 4,096 characters returns 400 invalid_value; a model named on this endpoint that is not a speech model returns 400 unsupported_for_model. See Errors.

Python

from openai import OpenAI

client = OpenAI(base_url="https://api.zabio.ai/v1", api_key="insert your zabio.ai key here")
with client.audio.speech.with_streaming_response.create(model="auto", input="Good morning.", response_format="mp3") as res:
    res.stream_to_file("morning.mp3")
    print(res.headers["x-zabio-model-served"], res.headers["x-zabio-cost-micros"])

CLI

zabio speak -o morning.mp3 "Good morning." writes the file and prints the model, the vendor and the cost; --model, --voice, --format and --speed as above.