Lightweight C library, viewer, and CLI toolset for PDF, XPS, and e-book formats: renders and extracts text/images/metadata/structured content; creates, splits, merges, and compresses PDFs; adds annotations (highlights, stamps, shapes); permanently redacts content; digitally signs documents; converts between PDF, SVG, PNG, HTML, and PostScript; and embeds into web pages/apps.
AGPL v3-or-later, with commercial licensing available from Artifex.