XO is a linter and code formatter enforcing strict, opinionated JavaScript coding standards with zero configuration. Built on ESLint, it promotes consistent style across projects, automatically fixing many issues. It includes best practices like using modern JavaScript syntax and preventing common errors. XO aims for developer efficiency, enabling focus on code logic rather than style debates, resulting in cleaner, more maintainable code.
The npm package xo has been released sporadically since May 2012. Releases were infrequent until August 2015, when they became more regular. The most releases in a single month occurred in August 2015 (11 releases) and May 2025 (8 releases). After 2021, monthly releases decreased significantly. The latest release was in August 2025.
XO npm package downloads showed steady growth from March 2024 to February 2025, averaging around 360,000 monthly. A significant surge began in April 2025, peaking in August at over 1.2 million downloads. September 2025 data is incomplete, showing no downloads as of today.
