ESLint

Last updated: Mar 2, 2026

Rationale

We use ESLint as the main static linter for TypeScript source code.

It is an old-school TypeScript linter, which means it has many rules implemented and has been thoroughly tested.
It is open source.
It has a huge number of typing checks.
It supports caching already-reviewed files for performance.
It provides a language server out of the box, considerably affecting development experience.
It integrates in-editor typing using its VS Code extension for the development experience.
As it is built in JavaScript, it has serious performance limitations.

Below are alternatives we are currently considering as possible replacements to ESLint:

Biome is a static linter and formatter, meaning that it not only replaces ESLint but also formatting tools like Prettier.
It is open source.
It does not have as many typing checks as ESLint, but is getting there very fast.
Although it currently does not support caching, it is still much faster compared to ESLint.
It provides a language server out of the box, considerably improving development experience.
It integrates in-editor typing using its VS Code extension for the development experience.
As it is built in Rust, it is considerably faster compared to other linters and formatters, up to a point where performance is no longer a concern.

Biome was last reviewed on Aug 5, 2025.

Oxc is a static linter; it does not support formatting yet.
It is open source.
It does not have as many typing checks as ESLint, but is getting there very fast.
Although it currently does not support caching, it is still much faster compared to ESLint.
It provides a language server out of the box, considerably improving development experience.
It integrates in-editor typing using its VS Code extension for the development experience.
As it is built in Rust, it is considerably faster compared to other linters and formatters, up to a point where performance is no longer a concern.

Oxc was last reviewed on Aug 5, 2025.

We use ESLint to enforce strict code quality on all of Fluid Attacks' TypeScript source code.