Suggestions for interval
The following packages have something in common with the package interval. The packages are ordered in decreasing similarity.
- phfparen: Parenthetic math expressions made simpler and less redundant
 - dynbrackets: Commands to simplify the syntax of dynamic math brackets
 - tkz-interval: Interval brackets made with TikZ
 - perfectcut: Nested delimiters that consistently grow regardless of the contents
 - ibrackets: Intelligent brackets
 - bracealign: Align braces under and over math expressions
 - enparen: Consistent nested brackets
 - rainbowbrackets: Automatic coloring of nested parentheses
 - longmath: Nested delimiter groups extending over multiple array cells or lines
 - embrac: Upright brackets in emphasised text
 - nl-interval: Represent intervals on the number line
 - context-interval-calendar: Date driven lists or lists driven by date-intervals
 - mathfont: Use TrueType and OpenType fonts in math mode
 - attrib: Attribution of block quotations in LaTeX
 - longnamefilelist: Tidy \listfiles with long file names
 - readprov: Provides GetFileInfo without the need to load the file
 - iffont: Conditionally load fonts with fontspec
 - blkcntrl: Block-element hooks in LaTeX
 - bits: Sub-document environments in LaTeX
 - zwgetfdate: Get package or file date
 - chapterfolder: Package for working with complicated folder structures
 - diagnose: A diagnostic tool for a TeX installation
 - dateiliste: Extensions of the \listfiles concept
 - getfiledate: Find the date of last modification of a file
 - messagebubbles: Display message bubbles as a conversation
 - newfile: User level management of LaTeX input and output
 - progress: Creates an overview of a document's state
 - statistik: Store statistics of a document
 - stampinclude: Inclusion based on .aux file date stamps
 - fileinfo: Enhanced display of LaTeX File Information
 - myfilist: Configuring the output of the \listfiles command