Suggestions for chemfig
The following packages have something in common with the package chemfig. The packages are ordered in decreasing similarity.
- etoolbox-generic: A loader for etoolbox.sty in non-LaTeX formats
 - visualtoks: Typeset TeXbook-style visualisations of token lists
 - chemplants: Symbology to draw chemical plants with TikZ
 - polexpr: A parser for polynomial expressions
 - witharrows: “Aligned” math environments with arrows for comments
 - schemata: Print topical diagrams
 - quickreaction: A simple and fast way to typeset chemical reactions
 - tikzorbital: Atomic and molecular orbitals using TikZ
 - texapi: Macros to write format-independent packages
 - eoldef: Define commands which absorb the whole source line as arguments
 - pdfmsym: PDF Math Symbols — various drawn mathematical symbols
 - reotex: Draw Reo Channels and Circuits
 - smartdiagram: Generate diagrams from lists
 - grafcet: Draw Grafcet/SFC with TikZ
 - messagepassing: Draw diagrams to represent communication protocols
 - adigraph: Augmenting directed graphs
 - syntaxdi: Create “railroad” syntax diagrams
 - sankey: Draw Sankey diagrams with TikZ
 - duotenzor: Drawing package for circuit and duotensor diagrams
 - pgf-periodictable: Create custom periodic tables of elements
 - pgfmolbio: Draw graphs typically found in molecular biology texts
 - pfdicons: Draw process flow diagrams in chemical engineering
 - tikz-trackschematic: A TikZ library for creating track diagrams in railways
 - tikz-network: Draw networks with TikZ
 - fast-diagram: Easy generation of FAST diagrams
 - simplenodes: Simple nodes in four colors written in TikZ for LaTeX
 - prisma-flow-diagram: An abstraction for creating PRISMA 2009 flow diagrams with TikZ
 - plainpkg: A minimal method for making generic packages
 - localloc: Macros for localizing TeX register allocations
 - pdftexcmds: LuaTeX support for pdfTeX utility functions
 - ltxcmds: Some LaTeX kernel commands for general use