XO

Judgement

What it is

Developer tool

What it does

An ESLint wrapper with strict built-in rules and formatting for JavaScript and TypeScript, so a project needs no ESLint config of its own.

Adopt it when

You want an opinionated lint setup with no decisions to make, as in many of Sindre Sorhus's packages.

Watch out

The rules are strict and opinionated, and it follows one maintainer's preferences.

Ready for

Production-ready

Runs as

Command line

Built with

TypeScript and ESLint

How established

Established: started 11 years ago, latest release v5.0.1.

What the license allows

You can build it into a product you sell, as long as you keep its copyright notice.

Judged on 2026-11-06 from the project's README and GitHub data. The license and age lines are worked out directly.

Built from

Follow it down: XO → TypeScript → Go → runs on a microchip

How compilers were built, back to punched paper tape

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