Estraverse is a JavaScript library that provides generic, configurable traversal and transformation utilities for ECMAScript ASTs. It lets developers walk, inspect, modify, or replace nodes in a syntax tree (e.g., produced by parsers like Esprima) using simple visitor callbacks, making it useful for linters, code analysers, and source‑to‑source tools. Target audience: developers building tooling that needs to process or manipulate JavaScript code programmatically.