Name: ACE-Step API: Text and Lyrics to Song Generator
Brand: magicapi
SKU: api-magicapi-text-to-music-generator-lucataco-ace-step
Availability: InStock
Author: API Market

Shashank Agarwal

# 🎵 Text-to-Music Generator API (lucataco ACE-Step)

## Overview
ACE-Step is a music generation model. Its developers describe it as a step towards a music generation foundation model.

Send style `tags` and optional `lyrics` to generate a song. Each request returns the URL of one MP3 file.

## Features
- **Style tags**: describe genre, instruments, tempo and mood in `tags`.
- **Lyrics with structure**: mark parts with `[verse]`, `[chorus]` and `[bridge]`; use `[instrumental]` or `[inst]` for instrumental music.
- **Length**: `duration` from 1 to 240 seconds (default 60).
- **Sampling control**: `number_of_steps` (10 to 200), `scheduler` (`euler` or `heun`) and `seed`.
- **Guidance control**: `guidance_type` (`apg`, `cfg` or `cfg_star`), `guidance_scale`, `granularity_scale`, `guidance_interval`, `guidance_interval_decay`, `min_guidance_scale`, `tag_guidance_scale` and `lyric_guidance_scale`.

## Use Cases
1. **Songs from your own lyrics**: generate a full track from lyrics and style tags.
2. **Background music**: instrumental tracks for videos, games and podcasts with `[instrumental]`.
3. **Demos and drafts**: try out a song idea in several styles by changing `tags`.

## Visual Examples
### Example Input
The example asks for a 60-second synth-pop track at 128 BPM with one verse and one chorus of original lyrics.

```json
{
  "seed": -1,
  "tags": "synth-pop, electronic, pop, synthesizer, drums, bass, piano, 128 BPM, energetic, uplifting, modern",
  "lyrics": "[verse]\nMorning light on the harbor\nCoffee steam and open sky\nEvery street is singing softly\nAs the city opens its eyes\n\n[chorus]\nWe are moving, we are bright\nRunning with the morning light\nEvery heartbeat finds the rhythm\nHolding on and taking flight",
  "duration": 60,
  "scheduler": "euler",
  "guidance_type": "apg",
  "guidance_scale": 15,
  "number_of_steps": 60,
  "granularity_scale": 10,
  "guidance_interval": 0.5,
  "min_guidance_scale": 3,
  "tag_guidance_scale": 0,
  "lyric_guidance_scale": 0,
  "guidance_interval_decay": 0
}
```

### Example Output
[Listen to the example output](https://blog.api.market/wp-content/uploads/2026/10/ace-step-output-nzmkxf2a-api-market.mp3)

## Input Parameters
| Field | Type | Required | Default | Allowed values | Description |
| --- | --- | --- | --- | --- | --- |
| `tags` | string | Yes | none |  | Text tags that guide the music, for example `epic,cinematic`. |
| `lyrics` | string | No | none |  | Lyrics for the music. Use `[verse]`, `[chorus]` and `[bridge]` to separate parts. Use `[instrumental]` or `[inst]` for instrumental music. |
| `duration` | number | No | `60` | 1 to 240 | Duration of the generated audio in seconds. |
| `number_of_steps` | integer | No | `60` | 10 to 200 | Number of inference steps. |
| `seed` | integer | No | `-1` |  | Random seed. Set to -1 to randomize. |
| `scheduler` | string | No | `euler` | `euler`, `heun` | Scheduler type. |
| `guidance_type` | string | No | `apg` | `apg`, `cfg`, `cfg_star` | Guidance type for classifier-free guidance. |
| `granularity_scale` | number | No | `10` | -100 to 100 | Omega scale for `apg` guidance, or the equivalent for the other guidance types. |
| `guidance_interval` | number | No | `0.5` | 0 to 1 | Guidance interval. |
| `guidance_interval_decay` | number | No | `0` | 0 to 1 | Guidance interval decay. |
| `guidance_scale` | number | No | `15` | 0 to 30 | Overall guidance scale. |
| `min_guidance_scale` | number | No | `3` | 0 to 100 | Minimum guidance scale. |
| `tag_guidance_scale` | number | No | `0` | 0 to 10 | Guidance scale for `tags`. |
| `lyric_guidance_scale` | number | No | `0` | 0 to 10 | Guidance scale for `lyrics`. |

## Pricing
- **Pay As You Go (PAYG) pricing**: you only pay for what you use.
- **Price**: $0.028 per API unit.
- **1 API unit = 1 successful request** that uses up to 25 seconds of processing time. A request that needs more processing time is billed one more unit for each started block of 25 seconds (for example, 26 to 50 seconds of processing is 2 units, $0.056).
- Longer `duration` and more `number_of_steps` take longer; a request that runs past 25 seconds of processing uses more than one unit.
- **Example cost**: the example request on this page used 5.6 seconds of processing, so it was billed 1 unit ($0.028).
- **Failed or cancelled predictions are not billed.**
- **GET requests to check prediction status** are free and don't count toward API unit usage.
- **No monthly subscription fee.**

## API Documentation

### Base URL
All API requests go to: `https://prod.api.market/api/v1/magicapi/text-to-music-generator-lucataco-ace-step`

### Authentication
Send your api.market API key in the `x-api-market-key` header:
```
x-api-market-key: YOUR_API_MARKET_KEY
```

### Asynchronous Processing
**IMPORTANT**: This API is asynchronous. The flow is:
1. Send a POST request to `/predictions`. A successful request returns **201 Created** with a prediction `id` and a `status` of `starting` or `processing`.
2. Poll GET `/predictions/{id}` with that ID.
3. Keep polling while `status` is `starting` or `processing`.
4. Stop when `status` is `succeeded` (read `output`), `failed` or `canceled` (read `error`).

A polling interval of 1 second and an overall timeout of 600 seconds (10 minutes) work well.

### Endpoints

#### Create a Prediction
```bash
curl -X POST "https://prod.api.market/api/v1/magicapi/text-to-music-generator-lucataco-ace-step/predictions" \
  -H "Content-Type: application/json" \
  -H "x-api-market-key: YOUR_API_MARKET_KEY" \
  -d '{
    "version": "280fc4f9ee507577f880a167f639c02622421d8fecf492454320311217b688f1",
    "input": {
      "seed": -1,
      "tags": "synth-pop, electronic, pop, synthesizer, drums, bass, piano, 128 BPM, energetic, uplifting, modern",
      "lyrics": "[verse]\nMorning light on the harbor\nCoffee steam and open sky\nEvery street is singing softly\nAs the city opens its eyes\n\n[chorus]\nWe are moving, we are bright\nRunning with the morning light\nEvery heartbeat finds the rhythm\nHolding on and taking flight",
      "duration": 60,
      "scheduler": "euler",
      "guidance_type": "apg",
      "guidance_scale": 15,
      "number_of_steps": 60,
      "granularity_scale": 10,
      "guidance_interval": 0.5,
      "min_guidance_scale": 3,
      "tag_guidance_scale": 0,
      "lyric_guidance_scale": 0,
      "guidance_interval_decay": 0
    }
  }'
```

Response (201 Created):
```json
{
  "id": "nzmkxf2a35rmw0d1d209x93jaw",
  "version": "280fc4f9ee507577f880a167f639c02622421d8fecf492454320311217b688f1",
  "status": "starting",
  "created_at": "2026-10-23T11:23:20.632Z"
}
```

#### Check Prediction Status
```bash
curl -X GET "https://prod.api.market/api/v1/magicapi/text-to-music-generator-lucataco-ace-step/predictions/{id}" \
  -H "x-api-market-key: YOUR_API_MARKET_KEY"
```

Response when the prediction has finished (200 OK):
```json
{
  "id": "nzmkxf2a35rmw0d1d209x93jaw",
  "status": "succeeded",
  "output": "https://blog.api.market/wp-content/uploads/2026/10/ace-step-output-nzmkxf2a-api-market.mp3",
  "error": null,
  "created_at": "2026-10-23T11:23:20.632Z",
  "started_at": "2026-10-23T11:23:56.957Z",
  "completed_at": "2026-10-23T11:24:02.549Z"
}
```

`output` is a single URL string pointing to the generated MP3 file.

### Status Codes
- **201 Created**: prediction created (POST `/predictions`). This is the normal success response.
- **200 OK**: prediction details returned (GET `/predictions/{id}`).
- **400 Bad Request**: invalid input, for example a missing `tags`, a `duration` above 240, or a `scheduler` other than `euler` or `heun`.
- **401 Unauthorized**: missing or invalid API key.
- **404 Not Found**: no prediction with that ID.
- **429 Too Many Requests**: rate limit exceeded.
- **500 Internal Server Error** or **503 Service Unavailable**: temporary server problem; retry later.

## Rate Limits
All plans allow 10 requests per second. Requests above that return `429 Too Many Requests`; back off before retrying and honour any `Retry-After` header. Polling a prediction with GET is free but still counts toward the per-second limit, so poll every 1 to 5 seconds rather than in a tight loop.

## Error Handling
- Check the HTTP status code of every request and read the response body for the error message.
- A prediction can also end with `status` set to `failed`; the `error` field then explains why. Failed predictions are not billed.
- Retry 429, 500 and 503 responses with exponential backoff. Fix the input before retrying a 400.

## Implementation Guide
### Example Code

#### JavaScript
```javascript
const apiKey = "YOUR_API_MARKET_KEY";
const baseUrl = "https://prod.api.market/api/v1/magicapi/text-to-music-generator-lucataco-ace-step";

async function createAndWaitForPrediction(input) {
  const response = await fetch(`${baseUrl}/predictions`, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      "x-api-market-key": apiKey
    },
    body: JSON.stringify({ version: "280fc4f9ee507577f880a167f639c02622421d8fecf492454320311217b688f1", input })
  });

  if (response.status !== 201) {
    throw new Error(`API error: ${response.status} ${await response.text()}`);
  }

  const prediction = await response.json();
  return pollForResults(prediction.id);
}

const delay = (ms) => new Promise((resolve) => setTimeout(resolve, ms));

async function pollForResults(predictionId) {
  const maxTimeout = 600000;
  const pollInterval = 1000;
  const startTime = Date.now();

  while (Date.now() - startTime < maxTimeout) {
    const response = await fetch(`${baseUrl}/predictions/${predictionId}`, {
      headers: { "x-api-market-key": apiKey }
    });

    if (!response.ok) {
      throw new Error(`API error: ${response.status} ${await response.text()}`);
    }

    const prediction = await response.json();

    if (prediction.status === "succeeded") {
      return prediction.output;
    }

    if (prediction.status === "failed" || prediction.status === "canceled") {
      throw new Error(`Prediction ${prediction.status}: ${prediction.error || "Unknown error"}`);
    }

    await delay(pollInterval);
  }

  throw new Error("Prediction timed out after 10 minutes");
}

createAndWaitForPrediction({
    "seed": -1,
    "tags": "synth-pop, electronic, pop, synthesizer, drums, bass, piano, 128 BPM, energetic, uplifting, modern",
    "lyrics": "[verse]\nMorning light on the harbor\nCoffee steam and open sky\nEvery street is singing softly\nAs the city opens its eyes\n\n[chorus]\nWe are moving, we are bright\nRunning with the morning light\nEvery heartbeat finds the rhythm\nHolding on and taking flight",
    "duration": 60,
    "scheduler": "euler",
    "guidance_type": "apg",
    "guidance_scale": 15,
    "number_of_steps": 60,
    "granularity_scale": 10,
    "guidance_interval": 0.5,
    "min_guidance_scale": 3,
    "tag_guidance_scale": 0,
    "lyric_guidance_scale": 0,
    "guidance_interval_decay": 0
  }).then((output) => console.log(output));
```

#### Python
```python
import time
import requests

API_KEY = "YOUR_API_MARKET_KEY"
BASE_URL = "https://prod.api.market/api/v1/magicapi/text-to-music-generator-lucataco-ace-step"


def create_and_wait_for_prediction(input_data):
    headers = {"Content-Type": "application/json", "x-api-market-key": API_KEY}
    response = requests.post(
        f"{BASE_URL}/predictions",
        headers=headers,
        json={"version": "280fc4f9ee507577f880a167f639c02622421d8fecf492454320311217b688f1", "input": input_data},
    )

    if response.status_code != 201:
        raise Exception(f"API error: {response.status_code} {response.text}")

    return poll_for_results(response.json()["id"])


def poll_for_results(prediction_id):
    max_timeout = 600
    poll_interval = 1
    headers = {"x-api-market-key": API_KEY}
    start_time = time.time()

    while time.time() - start_time < max_timeout:
        response = requests.get(f"{BASE_URL}/predictions/{prediction_id}", headers=headers)

        if response.status_code != 200:
            raise Exception(f"API error: {response.status_code} {response.text}")

        prediction = response.json()

        if prediction["status"] == "succeeded":
            return prediction["output"]

        if prediction["status"] in ("failed", "canceled"):
            raise Exception(f"Prediction {prediction['status']}: {prediction.get('error') or 'Unknown error'}")

        time.sleep(poll_interval)

    raise Exception("Prediction timed out after 10 minutes")


print(create_and_wait_for_prediction({
    "seed": -1,
    "tags": "synth-pop, electronic, pop, synthesizer, drums, bass, piano, 128 BPM, energetic, uplifting, modern",
    "lyrics": "[verse]\nMorning light on the harbor\nCoffee steam and open sky\nEvery street is singing softly\nAs the city opens its eyes\n\n[chorus]\nWe are moving, we are bright\nRunning with the morning light\nEvery heartbeat finds the rhythm\nHolding on and taking flight",
    "duration": 60,
    "scheduler": "euler",
    "guidance_type": "apg",
    "guidance_scale": 15,
    "number_of_steps": 60,
    "granularity_scale": 10,
    "guidance_interval": 0.5,
    "min_guidance_scale": 3,
    "tag_guidance_scale": 0,
    "lyric_guidance_scale": 0,
    "guidance_interval_decay": 0
}))
```

## FAQ
- **How do I make an instrumental track?**
  - Put `[instrumental]` or `[inst]` in `lyrics` and describe the style in `tags`.
- **How long can a track be?**
  - Up to 240 seconds. Set `duration` in seconds; the default is 60.
- **What format is the output?**
  - An MP3 file. `output` is its URL.
- **Is the 201 response from POST an error?**
  - No. 201 Created means the prediction was accepted. Use the returned `id` to poll GET `/predictions/{id}` until `status` is `succeeded`, `failed` or `canceled`.
- **What if my prediction fails?**
  - Failed predictions are not billed. Read the `error` field, adjust the input and try again.

## Contact Us
If you have any questions, reach out to us through the chat on the bottom right of the page. You can also email our support team at hello@magicapi.com.


Generate songs up to 240 seconds long from style tags and lyrics with ACE-Step, returned as MP3. $0.028 per API unit, pay as you go.