Format and beautify code for JavaScript, JSON, HTML, CSS, and TypeScript

Code Formatter — Consistent Style for JavaScript, Python, CSS, HTML, and More

Inconsistent code formatting is not a cosmetic problem — it is a collaboration and maintenance problem. A codebase where different contributors use different indentation styles (tabs versus spaces), different brace placement conventions (opening brace on same line versus next line), different maximum line lengths, and different quote style preferences (single versus double) produces diff output that conflates style changes with functional changes. Code review becomes harder because the reviewer must mentally filter out formatting noise to see whether the logic changed. Blame history in version control becomes polluted with reformatting commits. Code formatting tools eliminate this category of friction by enforcing a single consistent style across all contributors automatically.

Opinionated formatters versus configurable formatters represent a philosophy divide in the code formatting ecosystem. Prettier, the dominant JavaScript/TypeScript formatter, is intentionally opinionated — it makes most formatting decisions without user configuration, with the explicit goal that teams stop arguing about formatting and accept the formatter's output. gofmt, Go's built-in formatter, takes the same approach and has effectively eliminated formatting debates in the Go community entirely. Black, Python's uncompromising formatter, follows this philosophy. Configurable formatters like ESLint (with formatting rules) and EditorConfig allow teams to specify their style preferences but require upfront configuration work and ongoing configuration maintenance. The formatter offers both opinionated modes (apply Prettier-style formatting) and configurable modes for teams with existing style requirements.

Language-specific formatting rules reflect the idioms and conventions of each programming language's community. JavaScript formatting decisions include semicolons (required or ASI-style omission), quote character (single, double, or backtick for templates), trailing commas in multi-line lists (none, ES5-compatible, or all), and arrow function parentheses (always or only when needed). Python formatting follows PEP 8 — 4-space indentation, 79-character line limit, two blank lines between top-level definitions, one blank line between methods. CSS formatting affects property ordering (alphabetical versus grouped by purpose), whitespace around colons, and selector arrangement. The formatter applies language-appropriate rules based on the detected or specified language, producing output that matches community conventions rather than imposing cross-language uniformity.