Suggestions for Fitch

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

Package turnstile: Typeset the (logic) turnstile notation
Package ebproof: Formal proofs in the style of sequent calculus
Package prftree: Macros for building proof trees
Package bussproofs: Proof trees in the style of the sequent calculus
Package lkproof: LK Proof figure macros
Package gene-logic: Typeset logic formulae, etc.
Package proof-at-the-end: A package to move proofs to appendix
Package bussproofs-extra: Extra commands for bussproofs.sty
Package hideproofs: Defines a starred proof environment that hides proofs in draft mode
Package calculation: Typesetting reasoned calculations, also called calculational proofs
Package apxproof: Proofs in appendix
Package upgreek: Upright Greek letters
Package begriff: Typeset Begriffschrift
Package frege: Typeset fregean Begriffsschrift
Package grundgesetze: Typeset Frege’s Grundgesetze der Arithmetik
Package logictools: Additional tools for typesetting formal logic
Package synproof: Easy drawing of syntactic proofs
Package bussproofs-colorful: Color extension for the bussproofs package
Package centernot: Centred \not command
Package eqnlines: Single- and multiline equations
Package delimset: Typeset and declare sets of delimiters with convenient size control
Package extpfeil: Extensible arrows in mathematics
Package extarrows: Extra Arrows beyond those provided in amsmath
Package iwonamath: LaTeX support for scaled Iwona math fonts
Package letterswitharrows: Draw arrows over math letters
Package mathtools: Mathematical tools to use with amsmath
Package mattens: Matrices/tensor typesetting
Package mathpartir: Typesetting sequences of math formulas, e.g. type inference rules
Package mathbbol: Use the bbold fonts in mathematics
Package sansmath: Maths in a sans font
Package steinmetz: Print Steinmetz notation