Rules determine what the linter looks for and complains about. All the rules are turned off by default and none have default values for their options. The rules follow a consistent naming convention and have been designed to work in conjunction with one another, you can read more about this in the "About rules" section.
In addition to these rules there are plugins, which are rules built by the community that support methodologies, toolsets, non-standard CSS features, or very specific use cases. Don't forget to look at the list of plugins for more ways to lint.
Here are all the rules within stylelint, grouped first by category and then by the thing they apply to.
color-no-invalid-hex: Disallow invalid hex colors.
font-family-no-duplicate-names: Disallow duplicate font family names.
function-calc-no-unspaced-operator: Disallow an unspaced operator withincalcfunctions.function-linear-gradient-no-nonstandard-direction: Disallow direction values inlinear-gradient()calls that are not valid according to the standard syntax.
string-no-newline: Disallow (unescaped) newlines in strings.
unit-no-unknown: Disallow unknown units.
shorthand-property-no-redundant-values: Disallow redundant values in shorthand properties.
property-no-unknown: Disallow unknown properties.
keyframe-declaration-no-important: Disallow!importantwithin keyframe declarations.
declaration-block-no-duplicate-properties: Disallow duplicate properties within declaration blocks.declaration-block-no-redundant-longhand-properties: Disallow longhand properties that can be combined into one shorthand property.declaration-block-no-shorthand-property-overrides: Disallow shorthand properties that override related longhand properties within declaration blocks.
block-no-empty: Disallow empty blocks.
selector-pseudo-class-no-unknown: Disallow unknown pseudo-class selectors.selector-pseudo-element-no-unknown: Disallow unknown pseudo-element selectors.selector-type-no-unknown: Disallow unknown type selectors.
media-feature-name-no-unknown: Disallow unknown media feature names.
at-rule-no-unknown: Disallow unknown at-rules.
comment-no-empty: Disallow empty comments.
max-nesting-depth: Limit the depth of nesting.no-descending-specificity: Disallow selectors of lower specificity from coming after overriding selectors of higher specificity.no-duplicate-selectors: Disallow duplicate selectors.no-empty-source: Disallow empty sources.no-extra-semicolons: Disallow extra semicolons.no-invalid-double-slash-comments: Disallow double-slash comments (//...) which are not supported by CSS.no-unknown-animations: Disallow unknown animations.
color-named: Require (where possible) or disallow named colors.color-no-hex: Disallow hex colors.
function-blacklist: Specify a blacklist of disallowed functions.function-url-no-scheme-relative: Disallow scheme-relative urls.function-url-scheme-blacklist: Specify a blacklist of disallowed url schemes.function-url-scheme-whitelist: Specify a whitelist of allowed url schemes.function-whitelist: Specify a whitelist of allowed functions.
number-max-precision: Limit the number of decimal places allowed in numbers.
time-min-milliseconds: Specify the minimum number of milliseconds for time values.
unit-blacklist: Specify a blacklist of disallowed units.unit-whitelist: Specify a whitelist of allowed units.
value-no-vendor-prefix: Disallow vendor prefixes for values.
custom-property-pattern: Specify a pattern for custom properties.
property-blacklist: Specify a blacklist of disallowed properties.property-no-vendor-prefix: Disallow vendor prefixes for properties.property-whitelist: Specify a whitelist of allowed properties.
declaration-no-important: Disallow!importantwithin declarations.declaration-property-unit-blacklist: Specify a blacklist of disallowed property and unit pairs within declarations.declaration-property-unit-whitelist: Specify a whitelist of allowed property and unit pairs within declarations.declaration-property-value-blacklist: Specify a blacklist of disallowed property and value pairs within declarations.declaration-property-value-whitelist: Specify a whitelist of allowed property and value pairs within declarations.
declaration-block-single-line-max-declarations: Limit the number of declaration within single line declaration blocks.
selector-attribute-operator-blacklist: Specify a blacklist of disallowed attribute operators.selector-attribute-operator-whitelist: Specify a whitelist of allowed attribute operators.selector-class-pattern: Specify a pattern for class selectors.selector-id-pattern: Specify a pattern for id selectors.selector-max-attribute: Limit the number of attribute selectors in a selector.selector-max-class: Limit the number of classes in a selector.selector-max-combinators: Limit the number of combinators in a selector.selector-max-compound-selectors: Limit the number of compound selectors in a selector.selector-max-empty-lines: Limit the number of adjacent empty lines within selectors.selector-max-id: Limit the number of id selectors in a selector.selector-max-specificity: Limit the specificity of selectors.selector-max-type: Limit the number of type in a selector.selector-max-universal: Limit the number of universal selectors in a selector.selector-nested-pattern: Specify a pattern for the selectors of rules nested within rules.selector-no-qualifying-type: Disallow qualifying a selector by type.selector-no-vendor-prefix: Disallow vendor prefixes for selectors.selector-pseudo-class-blacklist: Specify a blacklist of disallowed pseudo-class selectors.selector-pseudo-class-whitelist: Specify a whitelist of allowed pseudo-class selectors.
media-feature-name-blacklist: Specify a blacklist of disallowed media feature names.media-feature-name-no-vendor-prefix: Disallow vendor prefixes for media feature names.media-feature-name-whitelist: Specify a whitelist of allowed media feature names.
custom-media-pattern: Specify a pattern for custom media query names.
at-rule-blacklist: Specify a blacklist of disallowed at-rules.at-rule-no-vendor-prefix: Disallow vendor prefixes for at-rules.at-rule-whitelist: Specify a whitelist of allowed at-rules.
comment-word-blacklist: Specify a blacklist of disallowed words within comments.
color-hex-case: Specify lowercase or uppercase for hex colors (Autofixable).color-hex-length: Specify short or long notation for hex colors (Autofixable).
font-family-name-quotes: Specify whether or not quotation marks should be used around font family names.
font-weight-notation: Require numeric or named (where possible)font-weightvalues.
function-comma-newline-after: Require a newline or disallow whitespace after the commas of functions.function-comma-newline-before: Require a newline or disallow whitespace before the commas of functions.function-comma-space-after: Require a single space or disallow whitespace after the commas of functions.function-comma-space-before: Require a single space or disallow whitespace before the commas of functions.function-max-empty-lines: Limit the number of adjacent empty lines within functions.function-name-case: Specify lowercase or uppercase for function names.function-parentheses-newline-inside: Require a newline or disallow whitespace on the inside of the parentheses of functions.function-parentheses-space-inside: Require a single space or disallow whitespace on the inside of the parentheses of functions.function-url-quotes: Require or disallow quotes for urls.function-whitespace-after: Require or disallow whitespace after functions.
number-leading-zero: Require or disallow a leading zero for fractional numbers less than 1.number-no-trailing-zeros: Disallow trailing zeros in numbers.
string-quotes: Specify single or double quotes around strings.
length-zero-no-unit: Disallow units for zero lengths.
unit-case: Specify lowercase or uppercase for units.
value-keyword-case: Specify lowercase or uppercase for keywords values.
value-list-comma-newline-after: Require a newline or disallow whitespace after the commas of value lists.value-list-comma-newline-before: Require a newline or disallow whitespace before the commas of value lists.value-list-comma-space-after: Require a single space or disallow whitespace after the commas of value lists.value-list-comma-space-before: Require a single space or disallow whitespace before the commas of value lists.value-list-max-empty-lines: Limit the number of adjacent empty lines within value lists.
custom-property-empty-line-before: Require or disallow an empty line before custom properties (Autofixable).
property-case: Specify lowercase or uppercase for properties.
declaration-bang-space-after: Require a single space or disallow whitespace after the bang of declarations.declaration-bang-space-before: Require a single space or disallow whitespace before the bang of declarations.declaration-colon-newline-after: Require a newline or disallow whitespace after the colon of declarations.declaration-colon-space-after: Require a single space or disallow whitespace after the colon of declarations.declaration-colon-space-before: Require a single space or disallow whitespace before the colon of declarations.declaration-empty-line-before: Require or disallow an empty line before declarations (Autofixable).
declaration-block-semicolon-newline-after: Require a newline or disallow whitespace after the semicolons of declaration blocks.declaration-block-semicolon-newline-before: Require a newline or disallow whitespace before the semicolons of declaration blocks.declaration-block-semicolon-space-after: Require a single space or disallow whitespace after the semicolons of declaration blocks.declaration-block-semicolon-space-before: Require a single space or disallow whitespace before the semicolons of declaration blocks.declaration-block-trailing-semicolon: Require or disallow a trailing semicolon within declaration blocks.
block-closing-brace-empty-line-before: Require or disallow an empty line before the closing brace of blocks.block-closing-brace-newline-after: Require a newline or disallow whitespace after the closing brace of blocks.block-closing-brace-newline-before: Require a newline or disallow whitespace before the closing brace of blocks.block-closing-brace-space-after: Require a single space or disallow whitespace after the closing brace of blocks.block-closing-brace-space-before: Require a single space or disallow whitespace before the closing brace of blocks.block-opening-brace-newline-after: Require a newline after the opening brace of blocks.block-opening-brace-newline-before: Require a newline or disallow whitespace before the opening brace of blocks.block-opening-brace-space-after: Require a single space or disallow whitespace after the opening brace of blocks.block-opening-brace-space-before: Require a single space or disallow whitespace before the opening brace of blocks.
selector-attribute-brackets-space-inside: Require a single space or disallow whitespace on the inside of the brackets within attribute selectors.selector-attribute-operator-space-after: Require a single space or disallow whitespace after operators within attribute selectors.selector-attribute-operator-space-before: Require a single space or disallow whitespace before operators within attribute selectors.selector-attribute-quotes: Require or disallow quotes for attribute values.selector-combinator-space-after: Require a single space or disallow whitespace after the combinators of selectors.selector-combinator-space-before: Require a single space or disallow whitespace before the combinators of selectors.selector-descendant-combinator-no-non-space: Disallow non-space characters for descendant combinators of selectors.selector-pseudo-class-case: Specify lowercase or uppercase for pseudo-class selectors.selector-pseudo-class-parentheses-space-inside: Require a single space or disallow whitespace on the inside of the parentheses within pseudo-class selectors.selector-pseudo-element-case: Specify lowercase or uppercase for pseudo-element selectors.selector-pseudo-element-colon-notation: Specify single or double colon notation for applicable pseudo-elements.selector-type-case: Specify lowercase or uppercase for type selector.
selector-list-comma-newline-after: Require a newline or disallow whitespace after the commas of selector lists.selector-list-comma-newline-before: Require a newline or disallow whitespace before the commas of selector lists.selector-list-comma-space-after: Require a single space or disallow whitespace after the commas of selector lists.selector-list-comma-space-before: Require a single space or disallow whitespace before the commas of selector lists.
rule-empty-line-before: Require or disallow an empty line before rules.
media-feature-colon-space-after: Require a single space or disallow whitespace after the colon in media features.media-feature-colon-space-before: Require a single space or disallow whitespace before the colon in media features.media-feature-name-case: Specify lowercase or uppercase for media feature names.media-feature-parentheses-space-inside: Require a single space or disallow whitespace on the inside of the parentheses within media features.media-feature-range-operator-space-after: Require a single space or disallow whitespace after the range operator in media features.media-feature-range-operator-space-before: Require a single space or disallow whitespace before the range operator in media features.
media-query-list-comma-newline-after: Require a newline or disallow whitespace after the commas of media query lists.media-query-list-comma-newline-before: Require a newline or disallow whitespace before the commas of media query lists.media-query-list-comma-space-after: Require a single space or disallow whitespace after the commas of media query lists.media-query-list-comma-space-before: Require a single space or disallow whitespace before the commas of media query lists.
at-rule-empty-line-before: Require or disallow an empty line before at-rules (Autofixable).at-rule-name-case: Specify lowercase or uppercase for at-rules names (Autofixable).at-rule-name-newline-after: Require a newline after at-rule names.at-rule-name-space-after: Require a single space after at-rule names.at-rule-semicolon-newline-after: Require a newline after the semicolon of at-rules.at-rule-semicolon-space-before: Require a single space or disallow whitespace before the semicolons of at rules.
comment-empty-line-before: Require or disallow an empty line before comments (Autofixable).comment-whitespace-inside: Require or disallow whitespace on the inside of comment markers.
indentation: Specify indentation (Autofixable).max-empty-lines: Limit the number of adjacent empty lines.max-line-length: Limit the length of a line.no-eol-whitespace: Disallow end-of-line whitespace.no-missing-end-of-source-newline: Disallow missing end-of-source newlines (Autofixable).