Free API and REST API

Free API

No key and no account. Send a file to POST https://audo.ai/api/try/<tool> and get the result back. Each tool processes the first part of the file for free, a few times a day.

curl -F file=@interview.wav https://audo.ai/api/try/remove-noise -o interview-clean.wav

Inputs

• file, or url for a public HTTPS link, for tools that take one file. Send the body as multipart/form-data, or as JSON when every input is a url.
• Join takes file (or url) 2 to 20 times, in order.
• Swap audio takes video and audio (or video_url and audio_url).
• Align a script takes file, plus a text field or a script file (TXT, SRT, or VTT, up to 2 MB).
• Options are the tool's inputs, with the same names and defaults as the MCP tools. Send numbers and booleans as text, and arrays, such as cut's ranges, as JSON. IDs and idempotency_key aren't accepted, and free and max_credits need an API key.
• format (json, srt, vtt, or txt) chooses what transcription and alignment return.
• A request takes up to 100 MB of files, with or without a key; without one, what its links fetch counts too. Links are fetched one at a time. Please send a User-Agent that names your agent.

Responses

• The request waits up to about 30 seconds and returns the result itself: the audio or video file, the transcript, or the media info JSON.
• Send Prefer: respond-async to get 202 as soon as the upload is checked.
• A job that's still running returns 202 with a link to check on it: /api/try/jobs/<job_id>?t=<token>. The link works for 1 hour.
• RateLimit-Policy and RateLimit say how many free uses are left. Audo-Processed-Seconds says how much of the file was processed, and Audo-Full-Price-Credits gives the price of the whole file.
• When the free uses run out, the API returns 429 with JSON that says which limit, when it resets, and how to get more.

Whole files with an API key

Send an API key from the API keys page, and the same request runs on your account: the whole file, paid with your credits and charged only if the job succeeds. Add an Idempotency-Key header (a new UUID for each request) to retry safely: the same key returns the same job. Uploads are still up to 100 MB; send a larger file with the REST API, which uploads in parts.

curl -H "Authorization: Bearer $AUDO_API_KEY" -F file=@interview.wav https://audo.ai/api/try/remove-noise -o interview-clean.wav

• Add free=true to process only the free part, or max_credits to cap the price. Both need a key.
• Without enough credits, the API answers 402 with the price and where to buy credits.

Free limits

Uses are counted per tool, per UTC day. The website and the API share one count for each visitor.

Without a key, one address can send 2 uploads at once (an account, 4). Another upload while those are still arriving gets 429 with Retry-After; send it again once one finishes.

Every tool

Remove noise

curl -F file=@interview.wav https://audo.ai/api/try/remove-noise -o interview-clean.wav

Enhance voice

curl -F file=@lecture.wav https://audo.ai/api/try/enhance-voice -o lecture-enhanced.wav

Transcribe

curl -F file=@interview.mp3 -F format=srt https://audo.ai/api/try/transcribe -o interview.srt

Align a script

curl -F file=@talk.mp3 -F script=@script.txt -F format=srt https://audo.ai/api/try/align-script -o talk.srt

Cut

curl -F file=@episode.mp3 -F 'ranges=[[0,12.5]]' https://audo.ai/api/try/cut -o episode-cut.mp3

Remove silence

curl -F file=@episode.wav https://audo.ai/api/try/remove-silence -o episode-tight.wav

Set loudness

curl -F file=@episode.wav -F target=podcast https://audo.ai/api/try/loudness -o episode-loud.wav

Convert

curl -F file=@episode.wav -F format=mp3 https://audo.ai/api/try/convert -o episode.mp3

Join files

curl -F file=@intro.mp3 -F file=@episode.mp3 -F file=@outro.mp3 https://audo.ai/api/try/join -o full-episode.mp3

Swap a video's audio

curl -F video=@talk.mp4 -F audio=@talk-clean.wav https://audo.ai/api/try/swap-audio -o talk-new.mp4

Media info

curl -F file=@interview.wav https://audo.ai/api/try/media-info

Remove filler words

curl -F file=@interview.mp3 https://audo.ai/api/try/remove-fillers -o interview-tight.mp3

Level speakers

curl -F file=@podcast.wav https://audo.ai/api/try/level-speakers -o podcast-leveled.wav

Mix tracks

curl -F file=@voice.wav -F file=@music.mp3 -F 'tracks=[{"role":"voice"},{"role":"music","volume_db":-6}]' -F duck=true https://audo.ai/api/try/mix -o voice-mix.wav

REST API

The REST API runs whole files with your credits. Its base address is https://audo.ai/api/v1. Send an API key from the API keys page as a bearer token:

curl https://audo.ai/api/v1/account -H "Authorization: Bearer $AUDO_API_KEY"

Run a tool

1. POST /api/v1/files with {"filename": "interview.wav", "sizeBytes": 48213000} returns the file and how to upload it: one link in upload (up to 100 MB), or, for files over 16 MB, multipart with the part size, a part link, and a complete link, all under one token.
2. Upload the bytes with PUT to upload.url. For parts, PUT part n (counting from 1) to multipart.partUrl with {n} replaced by n, then POST to multipart.completeUrl, which joins them or lists the parts to send again.
3. GET /api/v1/files/<file_id>?wait=30 until its status is ready. Its prices gives each tool's price for the file, in credits.
4. POST /api/v1/jobs with the tool and its inputs, in snake_case: {"tool": "remove_noise", "file_id": "file_8Kc2QmP4", "idempotency_key": "<a new UUID>"}. Add max_credits to cap the price, or "free": true for the free part.
5. GET /api/v1/jobs/<job_id> until its status is succeeded, failed, or cancelled. A job is charged only if it succeeds.
6. GET /api/v1/files/<output_file_id>/download returns a link that works for 15 minutes.

Endpoints

Errors

Errors are JSON: {"error": {"code": "...", "message": "...", "retryable": false, "nextAction": "..."}}. The message says what went wrong, and nextAction says what to do. Codes: bad_request, unauthorized, forbidden, not_found, conflict, idempotency_key_reused, insufficient_balance, over_spending_cap, free_limit_reached, free_budget_exhausted, free_disabled, file_not_ready, file_invalid, file_expired, file_too_large, file_too_long, unsupported_format, wrong_file_type, text_too_long, no_audio, ranges_outside, fetch_failed, limit_exceeded, upload_limit_reached, rate_limited, job_not_cancellable, tool_unavailable, build_mismatch, internal_error.

OpenAPI

The full description of the free API and the REST API is at https://audo.ai/api/openapi.json.