mupdf started simple but I think it also grew in a weird direction (large codebase, some reflow I think, a strange epub substandard support, etc .. all pretty useless to me and I'm not sure how optional it it ... so no longer as lightweight as it could be ...)
mupdf-1.16.1-source/build/release$ du -sh platform resources source thirdparty 524K platform 42M resources 7.2M source 6.6M thirdparty where resources is a directory with 155 fonts compressed and embedded into the exe. Following (the quite old) pdf this should be configurable https://ghostscript.com/~robin/mupdf_explored.pdf (ch. 18) I guess that mupdf's targets are windows/mac/Linux/Android but as a base tool (eg ebook reader make senses on Android). License is AGPL https://mupdf.com/license.html like GPL plus """ Network Use – However, AGPL also has some conditions even if you are not distributing the software. For example, if you are using the software on your own company's equipment, but you are making the functionality of the software available to users interacting with it remotely through a computer network, and you make any change to the software, you must make the source code for your changed version available to users of the software. Take care to ensure that during network deployment that there is no code change that could invoke the source code availability obligation. This special requirement of AGPL is in Section 13; see the GNU web site for more details. Bottom line, if you distribute our software, or make the functionality of the software available to users interacting with it remotely through a computer network, you must share your source code. """ and also the "Corresponding Source " subsection. -- luigi