Suggestions for standalone

The following packages have something in common with the package standalone. The packages are ordered in decreasing similarity.

Package subfiles: Individual typesetting of subfiles of a main document
Package docmute: Input files ignoring LaTeX preamble, etc.
Package subdocs: Multifile documents
Package extsizes: Extend the standard classes’ size options
Package simplecv: A simple class for writing curricula vitae
Package tugboat: LaTeX macros for TUGboat articles
Package childdoc: Directly compile \include’d child documents
Package combine: Bundle individual documents into a single document
Package minidocument: Creates miniature documents inside other LaTeX documents
Package newclude: Reimplemented \include system for LaTeX
Package latex-base: Base sources of LaTeX
Package letter: The standard LaTeX2ε letter document class
Package amsbook: LaTeX document class for AMS books
Package amsproc: LaTeX document class for AMS conference proceedings
Package amsart: LaTeX document class for AMS math journal articles
Package includex: Extended \include
Package includernw: Include .Rnw inside .tex
Package achemso: Support for American Chemical Society journal submissions
Package abntex2: Typeset technical and scientific Brazilian documents based on ABNT rules
Package acmart: Class for typesetting publications of ACM
Package upgreek: Upright Greek letters
Package babel-esperanto: Babel support for Esperanto
Package slashed: Put a slash through characters
Package dotlessj: Generates a dot-less j
Package chemarr: Arrows for chemists
Package centernot: Centred \not command
Package amsrefs: A LaTeX-based replacement for BibTeX
Package eqnlines: Single- and multiline equations
Package acronym: Expand acronyms at least once
Package appendix: Extra control of appendices
Package algorithms: A suite of tools for typesetting algorithms in pseudo-code