Music generation API

Live

Original background music and scores for your videos.

From $0.0156 per minute of audio across 4 modelsCheapestACE-Step

from $0.0156/min

Input

PromptpromptStyle, mood, instruments and tempo.

88 / 1,000

Try:

VocalsinstrumentalSung vocals, with your lyrics or lyrics written for you.No extra charge

LyricsoptionallyricsSung as written; leave it empty and lyrics are written for you.

147 / 4,000

Leave empty and lyrics are written for you.

Lengthduration30 s

Any length from 10 to 240 seconds, billed by the second.

30 s30 s

Example

Example outputMade with this prompt

uplifting acoustic folk, warm fingerpicked guitar, soft vocals, light percussion, 90 bpm

0:00 / 0:00

Compare Music generation API models

Every model behind this endpoint, with live prices. Try one in the playground or open its page.

CassetteAI Sound EffectsCassetteAI$0.013 per track
Cheapest
Page
ACE-StepACE Studio & StepFun$0.0156 per minute of audio
Page
CassetteAI MusicCassetteAI$0.026 per minute of audio (billed per started minute)
Page
Stable Audio 3 Small SFXStability AI$0.02678 per track
Page
Stable Audio 3 SmallStability AI$0.02821 per track
Page
Stable Audio 3Stability AI$0.04888 per track
$0.08 per track-38%
Page

Every model of this tool with its price
		Official			Lengths / sizes	Badges	Actions
CassetteAI Sound EffectsCassetteAI	$0.013 per track	No official price	—	—	1–30 s	Cheapest	Page
ACE-StepACE Studio & StepFun	$0.0156 per minute of audio	No official price	—	—	10–240 s		Page
CassetteAI MusicCassetteAI	$0.026 per minute of audio (billed per started minute)	No official price	—	—	10–180 s		Page
Stable Audio 3 Small SFXStability AI	$0.02678 per track	No official price	—	—	1–30 s		Page
Stable Audio 3 SmallStability AI	$0.02821 per track	No official price	—	—	10–120 s		Page
Stable Audio 3Stability AI	$0.04888 per track	$0.08 per track	-38%	—	10–380 s		Page

Call Music generation API from your code

One endpoint for every model above. Change the model field to switch.

POSThttps://api.opennan.com/v1/music/generations

GET/v1/models?category=musicEvery model of this endpoint, with prices

Get an API key
Create a key in the console. It uses the same balance as the playground.
Create a key

Send your first request

The same request the playground sends. Set OPENNAN_KEY to your key.

curl https://api.opennan.com/v1/music/generations \
  -H "Authorization: Bearer $OPENNAN_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"ace-step","prompt":"Warm lo-fi hip hop, soft piano, vinyl crackle, relaxed tempo","duration":30,"instrumental":true}'

# Then poll until "status" is "succeeded" or "failed":
curl https://api.opennan.com/v1/tasks/<task id> -H "Authorization: Bearer $OPENNAN_KEY"

Poll the task
The call answers right away with a task id. Ask for the task until it finishes:
GEThttps://api.opennan.com/v1/tasks/{id}
queued
Waiting for a worker
running
Being made
succeeded
Done: outputs[].url holds the files
failed
Failed: you are not charged

Parameters

Built from the live catalog: every value listed here is one the API accepts.

Parameters
Name	Type	Allowed values	Default	Effect on price
`model`requiredWhich model runs the call.	string	ace-step · stable-audio-3 · stable-audio-3-small · stable-audio-3-sfx · cassette-music · cassette-sfx	—	—
`prompt`requiredStyle, mood and instruments.	string	—	—	—
`lyrics`optionalWords to sing. Leave out for instrumental music.	string	—	—	—
`instrumental`optionalMusic with no vocals.	boolean	—	—	—
`duration`optionalLength of the track in seconds.	integer	1–380	—	Billed per second of audio
`callback_url`optionalWe send the finished task to this URL.	URL	—	—	—

Errors and how to fix them

401Missing or wrong key
Send the header Authorization: Bearer with a key from the console.
402Balance too low
Add credit in Billing, then send the same call again.
400A value is not accepted
Read error.message: it names the field. Use a value from the parameter table.
429Too many requests
Wait a few seconds and try again, waiting longer after each 429.

Add Opennan to your AI app

One install gives your AI every Opennan tool: video, images, chat, voice, music, sound effects, 3D, captions and dubbing. Pick your app and follow the steps.

MCP serverhttps://api.opennan.com/v1/mcp

Works in the Codex CLI, the Codex app and the Codex IDE extension: they share ~/.codex/config.toml. If the app or IDE does not see OPENNAN_KEY, use the config.toml option with your key in it. Codex asks before each tool call: approve it to go on.

Get an API key
Create a key in the console. It starts with sk- and uses the same balance as the website.
Create a key

Save your key as OPENNAN_KEY

# macOS / Linux (zsh shown; bash: ~/.bashrc)
echo 'export OPENNAN_KEY="sk-..."' >> ~/.zshrc
source ~/.zshrc

# Windows (PowerShell), then open a new terminal
setx OPENNAN_KEY "sk-..."

3
Install the Opennan plugin: the server plus a skill that teaches your AI to pick models, confirm prices and wait for results
```
codex plugin marketplace add Opennan/opennan-ai-plugin
codex plugin add opennan@opennan
```

Or add only the server

codex mcp add opennan --url https://api.opennan.com/v1/mcp --bearer-token-env-var OPENNAN_KEY

Or add this to ~/.codex/config.toml

[mcp_servers.opennan]
url = "https://api.opennan.com/v1/mcp"
http_headers = { Authorization = "Bearer sk-..." }

4
Check that opennan is listed
```
codex mcp list
```
Restart Codex, then ask for anything
“Make a 5 second video of rain on a neon street, a song to go with it and a poster image.”

Replace sk-... with your own key and keep it private: anyone who has it can spend your balance. Your app can list the tools before you add a key; making anything needs one.

This tool from your AI

Once Opennan is added, your AI calls this tool with arguments like these.

Tool: generate_music
Example arguments: { "model": "ace-step", "prompt": "Warm lo-fi hip hop, soft piano, vinyl crackle, relaxed tempo", "duration": 30 }

Music generation API: questions

Every model and price

How much does Music generation API cost?

From $0.0156 per minute of audio with ACE-Step, the cheapest of 4 models here. You see the price before you run.

How do I call it from my code?

Send POST https://api.opennan.com/v1/music/generations with your API key. It answers with a task id: ask https://api.opennan.com/v1/tasks/{id} until the task succeeds or fails.

Can I switch models without changing my code?

Yes. Change the model field and keep the rest of the request, the same key and the same balance.

Can my AI agent use it?

Yes. Add the MCP server https://api.opennan.com/v1/mcp and call the generate_music tool, or point your agent at https://api.opennan.com/llms.txt.

What happens if a run fails?

A failed run is not charged. You pay only for results.