libpng is the PNG image format reference implementation. Portable Network Graphics are the most widely used raster image format, patent-free, based on lossless data compression, support indexed/paletted, grayscale, and 24 or 32 bit truecolor images with transparency. It's also an highly extensible container format, with built-in color profiles and representation information, textual meta data, filters, progressive interlacing, and permits animations in the derived APNG or MNG formats.
PanConvert is a multi-platform GUI for instrumenting Pandoc to convert between various text, file and markup formats. It allows selecting files, or ad-hoc conversion of entered/pasted markup. Pandoc needs to be installed, and handles MarkDown/CommonMark, LaTeX, OPML, ODT and EPUB formats.
Uriparser is a RFC-conformant URI/IRI parsing library. It's cross-platform, written in C and thus speedy, and provides full Unicode support, reference resolution and creation, recomposition, and syntax-based normalization.
The eXtensible Binary Universal Protocol (XBUP) project is an attempt to design unified general binary data communication protocol and file format. It is based on the unlimited unary-binary encoding and block-tree structure with strong-type system and automatic transformations. Implementation should provide open-source libraries, editor tools, catalog of types and processing framework.