SXF is an open, JSON-based universal format for storing and synchronizing song lyrics. It's designed to be simple enough for user-generated content (UGC) and powerful enough for licensed, rich-lyrics APIs.

It elegantly scales from simple, unsynchronized text to complex, syllable-by-syllable synchronized lyrics for multiple vocalists.

Current lyrics formats are lacking:

• .LRC is widely supported but outdated. It only supports line-by-line timestamps and has no standard for translations or multiple singers.
• Proprietary JSON formats (from services like Musixmatch, Spotify, Apple Music) are powerful but are closed-source, complex, and not designed for interoperability or community content.

SXF aims to be the single, open standard that bridges this gap.

• Three Levels of Sync:
  1. Unsynced: Simple plain text lines.
  2. Line-Synced: Start and end timestamps for each line (Karaoke-style).
  3. Rich-Synced: Timestamps for every word or syllable.
• Song Structure: Semantically define verses, choruses, bridges, and more.
• Multiple Singers & Roles: Assign lines to different vocalists (duets) and define their roles (e.g. main, background).
• Semantic Details: Supports emphasis (bold/italic) per-segment and translations per-line.
• JSON Native: Fully compatible with JSON, making it trivial to parse in any language (JavaScript, Python, Java, etc.).
• Flexible & Robust: Gracefully handles files with only metadata (e.g. for instrumental tracks) by making lyrics optional.

The most basic format.

{
  "version": "1.0",
  "meta": {
    "title": "Twinkle Twinkle Little Star",
    "lang": "en"
  },
  "lyrics": [
    { "text": "Twinkle, twinkle, little star" },
    { "text": "How I wonder what you are" },
    { "text": "Up above the world so high" },
    { "text": "Like a diamond in the sky" }
  ]
}

Ideal for standard karaoke-style display.

{
  "version": "1.0",
  "meta": {
    "title": "Let It Go",
    "lang": "en"
  },
  "lyrics": [
    {
      "start": 10500,
      "end": 12800,
      "text": "The snow glows white on the mountain tonight",
      "translations": [
        { "lang": "ru", "text": "Снег блестит на горе сегодня ночью" }
      ]
    },
    {
      "start": 13100,
      "end": 15200,
      "text": "Not a footprint to be seen",
      "translations": [
        { "lang": "ru", "text": "Не видно ни следа" }
      ]
    }
  ]
}

The most powerful format, for "Apple Music" style animated lyrics and duets.

{
  "version": "1.0",
  "meta": {
    "title": "A Whole New World",
    "artist": "Aladdin & Jasmine",
    "singers": [
      { "id": "aladdin", "name": "Aladdin", "role": "main" },
      { "id": "jasmine", "name": "Jasmine", "role": "main" }
    ],
    "lang": "en"
  },
  "lyrics": [
    {
      "start": 20100,
      "end": 22500,
      "text": "I can show you the world",
      "singer": "aladdin",
      "segments": [
        { "text": "I ", "start": 20100, "end": 20300 },
        { "text": "can ", "start": 20300, "end": 20600 },
        { "text": "show ", "start": 20600, "end": 20900 },
        { "text": "you ", "start": 20900, "end": 21200 },
        { "text": "the ", "start": 21200, "end": 21400 },
        {
          "text": "world",
          "start": 21400,
          "end": 22500,
          "emphasis": "bold"
        }
      ]
    },
    {
      "start": 23000,
      "end": 25800,
      "text": "Shining, shimmering, splendid",
      "singer": "jasmine"
    }
  ]
}

The structure key is a top-level array that "points" to the lyrics array by index to define sections.

{
  "version": "1.0",
  "meta": {
    "title": "Twinkle Twinkle Little Star"
  },
  "lyrics": [
    { "text": "Twinkle, twinkle, little star" }, 
    { "text": "How I wonder what you are" }, 
    { "text": "Up above the world so high" }, 
    { "text": "Like a diamond in the sky" } 
  ],
  "structure": [
    {
      "type": "verse",
      "label": "Verse 1",
      "startIndex": 0,
      "endIndex": 1
    },
    {
      "type": "verse",
      "label": "Verse 2",
      "startIndex": 2,
      "endIndex": 3
    }
  ]
}

Even more examples can be found in the Examples folder.

This format is formally defined using JSON Schema. This allows anyone to validate their .sxf files to ensure they are correct.

• Full Specification: A human-readable guide to every field.
• JSON Schema: A machine-readable schema for validation.

A format is only as good as its tools. The immediate roadmap is focused on building a high-quality, open-source ecosystem for SXF.

• SXF Editor (In Development): A full-featured, open-source web (React) editor for creating and synchronizing .sxf files from scratch.
• SXF Player (In Development): A lightweight React component to easily parse and render SXF files with "Apple Music" style visualizations.
• [LRC to SXF Converter] (Planned): A simple online tool to migrate the huge library of existing .lrc files to the rich SXF format.
• [SXF Validator] (Planned): A schema-based validator, which will be available as an online tool.

This is an open project, and contributions are welcome! Whether you're helping to refine the specification, building a tool, or adding examples, your help is appreciated.

Please read our CONTRIBUTING.md guide to get started.

SXF is open-source and released under the Apache 2.0 License.