DjVu libraries for C/C++

• DjVuLibre is the only complete open-source DjVu implementation in C/C++. Its C API (ddjvuapi.h) decodes documents, renders pages into pixel buffers of any format, and returns the text layer, annotations and outline as s-expressions. The C++ classes underneath (DjVuDocument, JB2Image, IW44Image) also encode pages, but have no stable API. The library is GPL-2.0-or-later.
• djvudec is a decoder in plain C with no dependencies: render pages, extract text with word positions, read the outline and links. It’s about a seventh of the size of DjVuLibre, has a smaller API, ships as one .c + .h file, and is MIT-licensed. It doesn’t encode. SumatraPDF uses it.

Pick djvudec to view DjVu files or extract their text, especially when the GPL is a problem; DjVuLibre when you also need to create or edit DjVu files.

To create DjVu files from C/C++ code, most programs run the DjVuLibre tools (c44, cjb2, djvm, djvused) as separate processes. For a permissively licensed encoder, use djvu-rs (Rust, MIT).

• djvudec djvudec is a small plain-C DjVu decoder with no dependencies, MIT licensed. How to add it, render pages to pixels, extract text, read the outline.
• DjVuLibre DjVuLibre is the reference DjVu library and toolset. How to install it, open a DjVu document, render pages, extract the text layer.