epubcheck-ts

Validate EPUB files in Node.js and the browser. A TypeScript implementation of EPUBCheck.

Status: ~99% feature parity with Java EPUBCheck (1361 tests passing, 14 skipped). See PROJECT_STATUS.md for details. For full EPUB 3 conformance testing, use the official Java EPUBCheck.

Features

• CLI and API — Use as a CLI tool (npx @likecoin/epubcheck-ts book.epub) or import as a library
• Browser support — Works in Node.js 18+ and modern browsers via pure JS + WASM
• No native dependencies — No Java, no compilation — npm install and go
• TypeScript — Full type definitions included
• Tree-shakable — ESM with proper exports for minimal bundle impact

Try it Online

Live demo at likecoin.github.io/epubcheck-ts — validate EPUB files in the browser without uploading to any server.

Installation

npm install @likecoin/epubcheck-ts

Quick Start

Command Line Interface (CLI)

Quick validation:

npx @likecoin/epubcheck-ts book.epub

Or install globally:

npm install -g @likecoin/epubcheck-ts
epubcheck-ts book.epub

CLI Options:

epubcheck-ts <file.epub> [options]

Options:
  -j, --json <file>        Output JSON report to file (use '-' for stdout)
  -q, --quiet              Suppress console output (errors only)
  -p, --profile <name>     Validation profile (default|dict|edupub|idx|preview)
  -u, --usage              Include usage messages (best practices)
  -f, --fatal              Show only fatal errors
  -e, --error              Show fatal errors and errors
      --warn               Show fatal errors, errors, and warnings
  -c, --customMessages <file>  Override message severities (TSV: ID<tab>SEVERITY)
  -w, --fail-on-warnings   Exit with code 1 if warnings are found
  -l, --listChecks         List all message IDs and severities
  -v, --version            Show version information
  -h, --help               Show this help message

Examples:

# Basic validation
epubcheck-ts book.epub

# Generate JSON report
epubcheck-ts book.epub --json report.json

# Quiet mode for CI/CD
epubcheck-ts book.epub --quiet --fail-on-warnings

# Validate with specific profile
epubcheck-ts dictionary.epub --profile dict

# Show only errors (hide warnings/info)
epubcheck-ts book.epub --error

# Enable suppressed accessibility checks
printf "ACC-004\tWARNING\nACC-005\tWARNING\n" > overrides.txt
epubcheck-ts book.epub -c overrides.txt

ES Modules (recommended)

import { EpubCheck } from '@likecoin/epubcheck-ts';
import { readFile } from 'node:fs/promises';

// Load EPUB file
const epubData = await readFile('book.epub');

// Validate
const result = await EpubCheck.validate(epubData);

if (result.valid) {
  console.log('EPUB is valid!');
} else {
  console.log(`Found ${result.errorCount} errors and ${result.warningCount} warnings`);
  
  for (const message of result.messages) {
    console.log(`${message.severity}: ${message.message}`);
    if (message.location) {
      console.log(`  at ${message.location.path}:${message.location.line}`);
    }
  }
}

CommonJS

const fs = require('node:fs');

async function validate() {
  const { EpubCheck } = await import('epubcheck-ts');
  
  const epubData = fs.readFileSync('book.epub');
  const result = await EpubCheck.validate(epubData);
  
  console.log(result.valid ? 'Valid!' : 'Invalid');
}

validate();

Browser

import { EpubCheck } from '@likecoin/epubcheck-ts';

// From file input
const fileInput = document.querySelector('input[type="file"]');
fileInput.addEventListener('change', async (event) => {
  const file = event.target.files[0];
  const data = new Uint8Array(await file.arrayBuffer());
  
  const result = await EpubCheck.validate(data);
  console.log(result);
});

API

Full API reference: online | markdown

EpubCheck.validate(data, options?)

Static method to validate an EPUB file.

Parameters:

• data: Uint8Array - The EPUB file contents
• options?: EpubCheckOptions - Optional validation options

Returns: Promise<EpubCheckResult>

new EpubCheck(options?)

Create a reusable validator instance.

const checker = new EpubCheck({
  version: '3.3',
  profile: 'default',
  locale: 'en',
});

const result1 = await checker.check(epub1Data);
const result2 = await checker.check(epub2Data);

Options

interface EpubCheckOptions {
  /** EPUB version to validate against (auto-detected if not specified) */
  version?: '2.0' | '3.0' | '3.1' | '3.2' | '3.3';
  
  /** Validation profile */
  profile?: 'default' | 'edupub' | 'idx' | 'dict' | 'preview';
  
  /** Include usage messages in results (default: false) */
  includeUsage?: boolean;
  
  /** Include info messages in results (default: true) */
  includeInfo?: boolean;
  
  /** Maximum errors before stopping, 0 = unlimited (default: 0) */
  maxErrors?: number;
  
  /** Locale for messages (default: 'en') */
  locale?: string;
  
  /** Custom message severity overrides (message ID → severity) */
  customMessages?: Map<string, MessageSeverity>;
}

Result

interface EpubCheckResult {
  /** Whether the EPUB is valid (no errors or fatal errors) */
  valid: boolean;
  
  /** All validation messages */
  messages: ValidationMessage[];
  
  /** Counts by severity */
  fatalCount: number;
  errorCount: number;
  warningCount: number;
  infoCount: number;
  usageCount: number;
  
  /** Detected EPUB version */
  version?: string;
  
  /** Validation time in milliseconds */
  elapsedMs: number;
}

interface ValidationMessage {
  /** Unique message identifier (e.g., 'OPF-001') */
  id: string;
  
  /** Severity level */
  severity: 'fatal' | 'error' | 'warning' | 'info' | 'usage';
  
  /** Human-readable message */
  message: string;
  
  /** Location in the EPUB */
  location?: {
    path: string;
    line?: number;
    column?: number;
    context?: string;
  };
  
  /** Suggestion for fixing the issue */
  suggestion?: string;
}

JSON Report

Generate a JSON report compatible with the original EPUBCheck:

import { EpubCheck, Report } from '@likecoin/epubcheck-ts';

const result = await EpubCheck.validate(data);
const jsonReport = Report.toJSON(result);
console.log(jsonReport);

Supported Environments

| Environment | Version | Notes | |-------------|---------|-------| | Node.js | 18+ | Full support | | Chrome | 89+ | Full support | | Firefox | 89+ | Full support | | Safari | 15+ | Full support | | Edge | 89+ | Full support |

Architecture

This library is a TypeScript port of the Java-based EPUBCheck tool maintained by the W3C. Key implementation details:

• XML Processing: Uses libxml2-wasm for XML parsing and schema validation (RelaxNG, XSD) via WebAssembly
• ZIP Handling: Uses fflate for fast, lightweight EPUB container processing
• CSS Validation: Uses css-tree for CSS parsing and validation
• Schematron: Uses fontoxpath with slimdom for XPath 3.1 evaluation

Validation Coverage

| Component | Status | Completeness | Notes | |-----------|--------|--------------|-------| | OCF Container | 🟢 Complete | ~92% | ZIP structure, mimetype, container.xml, encryption.xml obfuscation | | Package Document (OPF) | 🟢 Complete | ~92% | Metadata, manifest, spine, collections, Schematron-equivalent checks | | Content Documents | 🟢 Complete | ~93% | XHTML structure, CSS url(), @import, SVG, entities, title, SSML, XML version | | Navigation Document | 🟢 Complete | ~95% | Nav content model, landmarks, labels, reading order, hidden, nested-ol | | Schema Validation | 🟡 Partial | ~55% | RelaxNG for OPF/container; XHTML/SVG disabled (libxml2 limitation) | | CSS | 🟡 Partial | ~85% | @font-face, @import, url() extraction, position, forbidden properties, alt style tags | | Cross-reference Validation | 🟢 Complete | ~92% | Reference tracking, fragments, fallbacks, remote resources, cross-document features | | Accessibility Checks | 🟢 Complete | ~71% | 12/17 ACC checks: table, image alt, hyperlink, MathML, SVG, epub:type, OPF metadata | | Media Overlays | 🟡 Partial | ~70% | SMIL structure, timing, audio, OPF metadata, duration validation | | Media Validation | 🟡 Partial | ~25% | Magic number checks (MED-004/OPF-029/PKG-022); deep format parsing planned |

Legend: 🟢 Complete | 🟡 Partial | 🔴 Basic | ❌ Not Started

Overall Progress: ~99% of Java EPUBCheck features

See PROJECT_STATUS.md for detailed comparison.

Development

Prerequisites

• Node.js 18+
• npm 9+

Setup

# Clone the repository
git clone https://github.com/likecoin/epubcheck-ts.git
cd epubcheck-ts

# Install dependencies
npm install

# Run tests
npm test

# Build
npm run build

Scripts

| Script | Description | |--------|-------------| | npm run build | Build the library (ESM + CJS) | | npm run dev | Build in watch mode | | npm test | Run tests in watch mode | | npm run test:run | Run tests once | | npm run test:coverage | Run tests with coverage | | npm run lint | Lint with ESLint | | npm run lint:fix | Lint and auto-fix | | npm run format | Format with Biome | | npm run typecheck | TypeScript type checking | | npm run check | Run all checks (format + typecheck) | | npm run docs | Generate API docs (HTML + Markdown) | | npm run docs:html | Generate HTML API docs to docs/html/ | | npm run docs:md | Generate Markdown API docs to docs/md/ |

Project Structure

epubcheck-ts/
├── src/
│   ├── index.ts           # Public API exports
│   ├── checker.ts         # Main EpubCheck class
│   ├── types.ts           # TypeScript type definitions
│   ├── core/              # Core validation logic
│   ├── ocf/               # OCF container validation ✅
│   ├── opf/               # Package document validation ✅
│   ├── content/           # Content document validation ✅
│   ├── nav/               # Navigation validation ✅
│   ├── ncx/               # NCX validation (EPUB 2) ✅
│   ├── references/        # Cross-reference validation ✅
│   ├── schema/            # Schema validation ✅
│   │   ├── relaxng.ts     # RelaxNG validation
│   │   ├── xsd.ts         # XSD validation
│   │   ├── schematron.ts  # Schematron validation
│   │   └── orchestrator.ts # Schema orchestration
│   └── messages/          # Error messages
├── schemas/               # Schema files (RNG, RNC, SCH)
├── test/
│   ├── fixtures/          # Test EPUB files
│   └── integration/       # Integration tests
├── docs/
│   └── md/                # Generated API docs (Markdown, checked in)
├── examples/
│   └── web/               # Web demo ✅
└── dist/                  # Build output

Legend: ✅ Implemented

Comparison with Java EPUBCheck

| Aspect | epubcheck-ts | EPUBCheck (Java) | |--------|--------------|------------------| | Runtime | Node.js / Browser | JVM | | Feature Parity | ~99% | 100% | | Bundle Size | ~450KB JS + ~1.6MB WASM | ~15MB | | Installation | npm install | Download JAR | | Integration | Native JS/TS | CLI or Java API | | Performance | Comparable | Baseline |

See PROJECT_STATUS.md for detailed feature comparison.

Contributing

Contributions are welcome! Please read CONTRIBUTING.md for guidelines.

For AI agents contributing to this project, see AGENTS.md.

License

GPL-3.0

This is an independent TypeScript implementation inspired by the Java-based EPUBCheck (BSD-3-Clause). No code was directly copied from the original project.

Acknowledgments

• W3C EPUBCheck - The original Java implementation
• DAISY Consortium - Maintainers of EPUBCheck
• libxml2-wasm - WebAssembly XML processing

Built by 3ook.com

This project is built and maintained by the 3ook.com team. 3ook is a Web3 eBook platform where authors can publish EPUB ebooks and readers can collect them as digital assets. If you're an author looking to publish your ebook, check out 3ook.com.

Related Projects

• EPUBCheck - Official Java validator
• epub.js - EPUB reader library
• r2-shared-js - Readium shared models