Suggestions for Chemfig

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

Package witharrows: Aligned math environments with arrows for comments
Package polexpr: A parser for polynomial expressions
Package etoolbox-generic: A loader for etoolbox.sty in non-LaTeX formats
Package tikz-cd: Create commutative diagrams with TikZ
Package pgf-periodictable: Create custom periodic tables of elements
Package visualtoks: Typeset TeXbook-style visualisations of token lists
Package quiver: Draw commutative diagrams exported from https://q.uiver.app
Package commutative-diagrams: CoDi: Commutative Diagrams for TeX
Package quantikz: Draw quantum circuit diagrams
Package trainmap: Draw railway line schematics and transit network maps with TikZ
Package chempid: Draw Piping and Instrumentation diagrams using TikZ via PGF
Package schemata: Print topical diagrams
Package zx-calculus: A library to typeset ZX Calculus diagrams
Package tikz-nef: Create diagrams for neural networks constructed with the methods of the Neural Engineering Framework (NEF)
Package chemplants: Symbology to draw chemical plants with TikZ
Package mohelper: Draw fully customizeable MO diagrams
Package orbitals: Atomic subshell / orbital-box diagrams for LaTeX, with automatic electron filling following Hund’s rule and the Pauli principle
Package tikz-sfc: Symbols collection for typesetting Sequential Function Chart (SFC) diagrams (PLC programs)
Package atableau: A LaTeX package for symmetric group combinatorics
Package ltxcmds: Some LaTeX kernel commands for general use
Package namedef: TeX definitions with named parameters
Package pdftexcmds: LuaTeX support for pdfTeX utility functions
Package collargs: Collect arguments of any command
Package tikz-relay: TikZ library for typesetting electrical diagrams
Package tikz-ladder: Draw ladder diagrams using TikZ
Package memoize: Externalization of graphics and memoization of compilation results in general
Package sankey: Draw Sankey diagrams with TikZ
Package texdimens: Conversion of TeX dimensions to decimals
Package tikz-network: Draw networks with TikZ
Package hologo: A collection of logos with bookmark support
Package iftex: Am I running under pdfTeX, XeTeX or LuaTeX?