Suggestions for leftindex

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

Package fouridx: Left sub- and superscripts in maths mode
Package leftidx: Left and right subscripts and superscripts in math mode
Package subdepth: Unify maths subscript height
Package tensor: Typeset tensors
Package tensind: Typeset tensors
Package altsubsup: Subscripts and superscripts with square brackets
Package tensorstyles: A package separating the content of tensors from their forms
Package isotope: A package for typesetting isotopes
Package subsupscripts: A range of sub- and superscript commands
Package realscripts: Access OpenType subscript and superscript glyphs
Package spbmark: Customize superscripts and subscripts
Package nuc: Notation for nuclear isotopes
Package bigints: Writing big integrals
Package commath: Mathematics typesetting support
Package diffcoeff: Write differential coefficients easily and consistently
Package derivative: Nice and easy derivatives
Package esdiff: Simplify typesetting of derivatives
Package fixmath: Make maths comply with ISO 31-0:1992 to ISO 31-13:1992
Package mleftright: Variants of delimiters that act as maths open/close
Package icomma: Intelligent commas for decimal numbers
Package mlist: Logical markup for lists
Package upgreek: Upright Greek letters
Package optidef: Environments for writing optimization problems
Package mhsetup: The mathtools setup function
Package autobreak: Simple line breaking of long formulae
Package abraces: Asymmetric over-/underbraces in maths
Package eqnarray: More generalised equation arrays with numbering
Package thmtools: Extensions to theorem environments
Package sfmath: Sans-serif mathematics
Package spalign: Typeset matrices and arrays with spaces and semicolons as delimiters
Package newproof: Make commands to define proofs