Difftastic is a tool for highlighting differences between code files in a syntax-aware way. This is quite different from textual diffing tools, like the venerable Unix diff command. For example, Difftastic will ignore newlines inserted to break up long statements in languages like Java or TypeScript that are semicolon delimited. The tool only highlights changes that impact the syntax of the program. It does this by first parsing the files into abstract syntax trees and then computing the distance between them using Dijkstra's algorithm. We've found Difftastic to be particularly useful for understanding changes when reviewing large codebases. Difftastic can be used on any programming language for which a parser is available and out of the box supports more than 50 programming languages as well as structured text formats like CSS and HTML. This isn't a new tool, but we thought it was worth calling attention to in the age of LLM coding assistants where human-in-the-loop reviews of ever larger codebases are increasingly critical.
