Skip to main content
One of Ultracite’s best features is that it’s zero-config out of the box — you can just extend the base preset and get going. However, every project is different, and you might want to customize certain rules or adapt Ultracite for different frameworks.

​
Framework Presets

Ultracite provides framework-specific configurations that you can extend in addition to the base core configuration. This allows you to add framework-specific linting rules without bloating the base config or dealing with irrelevant rules. The pattern is the same across all supported linters — import the core preset, then add any framework presets you need: 
ultracite/{linter}/core
ultracite/{linter}/{framework}
For example, if you’re using Biome with React and Next.js, you can pull in the following presets:
biome.jsonc
{
  "extends": [
    "ultracite/biome/core",
    "ultracite/biome/react",
    "ultracite/biome/next"
  ]
}

​
Default Configuration

When you include the core preset, you’re pulling in Ultracite’s base configuration. This preset includes framework-agnostic rules and settings. Some notable aspects:
  • TypeScript strictness: Enables strict checks and lint rules requiring robust typing. Discourages use of any, requires handling of null/undefined, and prefers explicit types where needed.
  • Best practices: Common rules like no unused vars, no explicit eval, no prototype pollution, etc.
  • Accessibility: ARIA attributes, semantic HTML, keyboard navigation, and other a11y rules are enabled by default.
  • Formatting conventions: 2-space indentation, 80-character line width, semicolons, trailing commas, and double quotes.
All these defaults aim to enforce consistent style and prevent common errors without manual configuration.

​
Safe Fixes

Most Ultracite rules only report errors — they don’t automatically modify your code. However, a few rules are configured with "fix": "safe", meaning they will auto-fix when you run ultracite fix. These fixes are non-breaking and safe to apply automatically:
RuleDescription
noUnusedImportsRemoves unused import statements
useBlockStatementsWraps single-line control flow bodies in curly braces
useSortedClassesSorts Tailwind CSS classes into a consistent order
If you want to disable auto-fixing for any of these, override the rule in your config and remove the fix property.

​
Overriding Rules

Each linter has its own way to disable or modify rules. For example, to disable the noAutofocus rule for Biome, you can do the following:
biome.jsonc
{
  "extends": ["ultracite/biome/core"],
  "linter": {
    "rules": {
      "a11y": {
        "noAutofocus": "off"
      }
    }
  }
}