Suggestions for IfxpTeX

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

Package iftex: Am I running under pdfTeX, XeTeX or LuaTeX?
Package tex-locale: Localisation support for TeX and LaTeX documents
Package ifvtex: Detects use of VTeX and its facilities
Package ifluatex: Provides the \ifluatex switch
Package ifpdf: Provides the \ifpdf conditional
Package ifetex: Provides \ifetex switch
Package ifxetex: Am I running under XeTeX?
Package ifptex: Check if the engine is pTeX or one of its derivatives
Package iflang: Expandable checks for the current language
Package ifplatform: Conditionals to test which platform is being used
Package ifdraft: Detect draft and final class options
Package arrayjob: Array data structures for (La)TeX
Package arrayjobx: Array data structures for (La)TeX
Package gates: Support for writing modular and customisable code
Package gtl: Manipulating generalized token lists
Package commado: Expandable iteration on comma-separated and filename lists
Package fenixpar: One-shot changes to token registers such as \everypar
Package dowith: Apply a command to a list of items
Package collargs: Collect arguments of any command
Package localloc: Macros for localizing TeX register allocations
Package plainpkg: A minimal method for making generic packages
Package etoolbox-generic: A loader for etoolbox.sty in non-LaTeX formats
Package advice: Extend commands and environments
Package balancedquotes: Code balanced quotes according to document language
Package multido: A loop facility for Generic TeX
Package multiexpand: Variations on the primitive command \expandafter
Package midnight: A set of useful macro tools
Package texapi: Macros to write format-independent packages
Package bitelist: Split list, in TeX’s mouth
Package gobble: More gobble macros for PlainTeX and LaTeX
Package lambda-lists: Lists in TeX’s mouth