UNDMS

High-performance document text and metadata extraction library with similarity comparison, built with napi-rs for Node.js and Bun.

Installation

pnpm add undms

Features

• Multi-format extraction - Text, DOCX, XLSX, PPTX, PDF, and images
• Similarity comparison - Compare documents against reference texts using multiple algorithms
• Rich metadata - Extract format-specific metadata (EXIF, PDF info, DOCX stats, etc.)
• OCR support - Extract text from images using Tesseract
• Parallel processing - Documents are processed concurrently for performance
• TypeScript support - Full type definitions included

Supported Formats

Format	MIME Type	Features
Text	text/*, application/json, application/xml, etc.	Content + line/word/character counts
DOCX	application/vnd.openxmlformats-officedocument.wordprocessingml.document	Paragraphs, tables, images, hyperlinks
XLSX	application/vnd.openxmlformats-officedocument.spreadsheetml.sheet	Cell content, sheets, rows, columns
PPTX	application/vnd.openxmlformats-officedocument.presentationml.presentation	Slide text, title, author, subject, slide count
PDF	application/pdf	Text, title, author, subject, producer, page info
Images	image/jpeg, image/png, image/gif, image/bmp, image/tiff, image/webp	OCR text, EXIF data, GPS location

Quick Start

import { extract, computeDocumentSimilarity, computeTextSimilarity } from 'undms';

const documents = [
  {
    name: 'report.txt',
    size: 1024,
    type: 'text/plain',
    lastModified: Date.now(),
    webkitRelativePath: '',
    buffer: Buffer.from('Document content here...'),
  },
];

const result = extract(documents);
console.log(result[0].documents[0].content);

API Reference

extract(documents)

Extracts text and metadata from input documents. Results are grouped by MIME type.

Parameters:

• documents - Array of Document objects

Returns: GroupedDocuments[]

const result = extract([
  {
    name: 'document.pdf',
    size: 1024,
    type: 'application/pdf',
    lastModified: Date.now(),
    webkitRelativePath: '',
    buffer: Buffer.from(pdfData),
  },
]);

computeDocumentSimilarity(documents, referenceTexts, threshold?, method?)

Extracts documents and computes similarity against reference texts.

Parameters:

• documents - Array of Document objects
• referenceTexts - Candidate reference texts to compare against
• threshold - Minimum score (0-100) to include a match (default: 30)
• method - Similarity algorithm: 'jaccard', 'ngram', 'levenshtein', or 'hybrid' (default)

Returns: GroupedDocumentsWithSimilarity[]

const result = computeDocumentSimilarity(
  documents,
  ['reference text A', 'reference text B'],
  70,
  'hybrid',
);

computeTextSimilarity(sourceText, referenceTexts, threshold?, method?)

Computes similarity for plain text without file extraction.

Parameters:

• sourceText - Source text to compare
• referenceTexts - Candidate reference texts
• threshold - Minimum score (0-100) to include a match (default: 30)
• method - Similarity algorithm (default: 'hybrid')

Returns: SimilarityMatch[]

const matches = computeTextSimilarity(
  'alpha beta gamma',
  ['alpha beta gamma', 'different text'],
  80,
  'jaccard',
);

Type Definitions

Document

Input document interface.

interface Document {
  name: string;
  size: number;
  type: string; // MIME type
  lastModified: number;
  webkitRelativePath: string;
  buffer: Buffer;
}

DocumentMetadata

Extracted document result.

interface DocumentMetadata {
  name: string;
  size: number;
  processingTime: number;
  encoding: string;
  content: string;
  metadata?: MetadataPayload;
  error?: string;
}

GroupedDocuments

Documents grouped by MIME type.

interface GroupedDocuments {
  mimeType: string;
  documents: DocumentMetadata[];
}

GroupedDocumentsWithSimilarity

Grouped documents with similarity matches.

interface GroupedDocumentsWithSimilarity {
  mimeType: string;
  documents: DocumentMetadataWithSimilarity[];
}

DocumentMetadataWithSimilarity

Document metadata with similarity results.

interface DocumentMetadataWithSimilarity {
  name: string;
  size: number;
  processingTime: number;
  encoding: string;
  content: string;
  metadata?: MetadataPayload;
  error?: string;
  similarityMatches: SimilarityMatch[];
}

SimilarityMatch

Similarity comparison result.

interface SimilarityMatch {
  referenceIndex: number;
  similarityPercentage: number;
}

MetadataPayload

Complete metadata payload with format-specific fields.

interface MetadataPayload {
  text?: TextMetadata;
  docx?: DocxMetadata;
  xlsx?: XlsxMetadata;
  pptx?: PptxMetadata;
  pdf?: PdfMetadata;
  image?: ImageMetadata;
}

TextMetadata

Text content statistics.

interface TextMetadata {
  lineCount: number;
  wordCount: number;
  characterCount: number;
  nonWhitespaceCharacterCount: number;
}

DocxMetadata

DOCX document statistics.

interface DocxMetadata {
  paragraphCount: number;
  tableCount: number;
  imageCount: number;
  hyperlinkCount: number;
}

XlsxMetadata

XLSX spreadsheet statistics.

interface XlsxMetadata {
  sheetCount: number;
  sheetNames: string[];
  rowCount: number;
  columnCount: number;
  cellCount: number;
}

PptxMetadata

PPTX presentation information.

interface PptxMetadata {
  title?: string;
  author?: string;
  subject?: string;
  slideCount: number;
}

PdfMetadata

PDF document information.

interface PdfMetadata {
  title?: string;
  author?: string;
  subject?: string;
  producer?: string;
  pageSize?: PdfPageSize;
  pageCount: number;
}

interface PdfPageSize {
  width: number;
  height: number;
}

ImageMetadata

Image file information.

interface ImageMetadata {
  width: number;
  height: number;
  format?: string;
  cameraMake?: string;
  cameraModel?: string;
  datetimeOriginal?: string;
  location: ImageLocation;
}

interface ImageLocation {
  latitude?: number;
  longitude?: number;
}

Similarity Methods

Method	Description
jaccard	Set-based similarity using Jaccard index
ngram	N-gram token matching (default: trigrams)
levenshtein	Edit distance-based similarity
hybrid	Weighted combination of all methods (default)

The similarity score is computed as a weighted blend of content similarity (80%) and metadata similarity (20%).

Error Handling

All functions handle errors gracefully:

• Extraction errors - Returned in the error field of DocumentMetadata
• Unsupported formats - Returns empty content with application/octet-stream encoding
• Similarity errors - Returns empty matches array

const result = extract(documents);
if (result[0].documents[0].error) {
  console.error('Extraction failed:', result[0].documents[0].error);
}

Troubleshooting

• OCR is slow - Large images take time; consider resizing before processing
• Missing GPS data - Not all images contain EXIF location; location object exists but fields may be undefined
• Empty PDF text - Some PDFs are image-based; OCR is not currently applied to PDFs
• Unicode handling - All similarity methods support Unicode text

Development

Requirements

• Rust (latest stable)
• Node.js 18+
• pnpm

Build

pnpm build

Test

pnpm test

Benchmark

pnpm bench

License

MIT