C++17 library for reading, writing, and modifying PDFs: full-featured low-level Unicode text extraction (with CJK support), text drawing with automatic CID encoding and font subsetting, incremental-update saving, PAdES-B digital signing (RSA/ECDSA, async), and PDF/A and PDF/UA compliance preservation when adding annotations or form fields. Does not yet render PDF content, and text shaping/kerning is limited.