Structured Data Extraction from PDFs: Regex vs Template Matching vs AI

Invoice processing is one of those problems that looks simple until you actually try to build it. Reading data from a PDF invoice should be straightforward - but the moment you encounter 50 different vendor layouts, foreign languages, scanned images, and multi-page documents, your initial approach falls apart. Here's an honest comparison of the three main approaches. Approach 1: Regex and String Parsing For a single, controlled invoice format, regex works fine: function extractInvoiceData ( text ) { const invoiceNumber = text.