You can explore following libraries,

1. PDF-LIB: A lightweight JavaScript library for creating and modifying PDF documents, supporting custom metadata and embedded files for advanced use cases. GitHub: https://github.com/Hopding/pdf-lib Documentation: https://pdf-lib.js.org/
2. PDFKit: A JavaScript library for generating PDF documents, allowing file embedding and metadata customization, useful for building complex PDFs. GitHub: https://github.com/foliojs/pdfkit Documentation: https://pdfkit.org/
3. HummusJS: A Node.js library for low-level PDF manipulation, ideal for embedding files and adding metadata required for PDF/A compliance. GitHub: https://github.com/galkahana/HummusJS NPM: https://www.npmjs.com/package/hummus