epubcheck-ts

A TypeScript port of EPUBCheck - the official conformance checker for EPUB publications.

Note: This library is primarily developed for internal use at 3ook.com and is built with AI-assisted development. While it has comprehensive test coverage (892 passing / 945 total tests) and ~88% feature parity with Java EPUBCheck, it may not be suitable for mission-critical production workloads. For production environments requiring full EPUB validation, consider using the official Java EPUBCheck. Contributions and feedback are welcome!

Features

• CLI and programmatic API: Use as a command-line tool or integrate into your application
• Cross-platform: Works in Node.js (18+) and modern browsers
• Partial EPUB validation: Currently ~88% of EPUBCheck feature parity
• Zero native dependencies: Pure JavaScript/WebAssembly, no compilation required
• TypeScript first: Full type definitions included
• Tree-shakable: ESM with proper exports for optimal bundling

Try it Online

Try the live demo at likecoin.github.io/epubcheck-ts - validate your EPUB files directly in the browser without uploading to any server.

Installation

npm install @likecoin/epubcheck-ts
Copy

Quick Start

Command Line Interface (CLI)

Quick validation:

npx @likecoin/epubcheck-ts book.epub
Copy

Or install globally:

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

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)
  -w, --fail-on-warnings   Exit with code 1 if warnings are found
  -v, --version            Show version information
  -h, --help               Show this help message
Copy

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
Copy

Note: This CLI provides ~88% coverage of Java EPUBCheck features. For complete EPUB 3 conformance testing, use the official Java EPUBCheck.

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}`);
    }
  }
}
Copy

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();
Copy

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);
});
Copy

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);
Copy

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;
}
Copy

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;
}
Copy

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);
Copy

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	🟡 Partial	~90%	ZIP structure, mimetype, container.xml, encryption.xml obfuscation
Package Document (OPF)	🟢 Complete	~90%	Metadata, manifest, spine, collections, Schematron-equivalent checks
Content Documents	🟡 Partial	~85%	XHTML structure, CSS url(), @import, SVG, entities, title, SSML, XML version
Navigation Document	🟢 Complete	~85%	Nav content model, landmarks, labels, reading order, hidden
Schema Validation	🟡 Partial	~50%	RelaxNG for OPF/container; XHTML/SVG disabled (libxml2 limitation)
CSS	🟡 Partial	~70%	@font-face, @import, url() extraction, position, forbidden properties
Cross-reference Validation	🟢 Complete	~90%	Reference tracking, fragments, fallbacks, remote resources
Accessibility Checks	🟡 Partial	~30%	Basic checks only (empty links, image alt, SVG titles)
Media Overlays	❌ Not Started	0%	Planned
Media Validation	❌ Not Started	0%	Planned

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

Overall Progress: ~88% 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
Copy

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
Copy

Legend: ✅ Implemented

Comparison with Java EPUBCheck

Aspect	epubcheck-ts	EPUBCheck (Java)
Runtime	Node.js / Browser	JVM
Feature Parity	~88%	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

Note: epubcheck-ts is currently in active development. 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