Concordance is a Node.js package designed to generate concordance lists from text. It provides a simple and efficient way to index words and their locations within a given document or body of text. Key features include case-insensitive indexing, stop word filtering, and customizable context window sizes. This package is valuable for text analysis, natural language processing tasks, and creating indices for large text corpora. It's useful for researchers, developers, and anyone needing to explore word usage within texts.