pdfme

pdfme is a free, open-source toolkit for creating and filling PDF documents programmatically. At its core, it uses a JSON-based template system. You define a layout with text fields, images, and other elements in a schema, and the library merges your data into that template to produce a finished PDF. This approach separates the design of a document from the data that populates it, making it highly reusable.

The library is written in TypeScript and offers several key components that work together or independently. The Generator is the main engine that produces PDFs at high speed. The Designer is a visual, WYSIWYG editor that lets you build templates without writing JSON by hand; it's a vanilla JavaScript web component you can embed in any project. There's also a Form module that creates fillable web forms based on your templates, collecting user input that can then be fed directly into the Generator.

This tool is ideal for developers who need to automate document creation within their applications, such as generating invoices, reports, certificates, or contracts. It's particularly useful for SaaS products, internal business tools, or any project where producing consistent, formatted PDFs from dynamic data is a requirement. Being open-source under the MIT license means there are no costs or restrictions for its PDF generation capabilities.