Why this tool is useful
Normalize a pasted code or markup fragment before review, documentation or a small local edit without sending proprietary source to a formatting API.
Developer & Data · runs locally
Private Code Formatter
Format JavaScript, TypeScript, HTML, CSS, SCSS, Less, Markdown, YAML or JSON with a pinned Prettier engine that runs only in this browser.
Ready. Your working data stays in this browser.
How it works
The page lazily loads an immutable local copy of Prettier 3.9.6 and its official browser plugins, applies only bounded explicit options and returns a downloadable text file.
Practical example
Choose TypeScript, paste an untidy component, set an 80-column width and compare the formatted result before replacing anything in the project.
Validation
The calculation is deterministic and explains validation errors instead of silently changing invalid input.
Privacy boundary
Input and output remain in this tab. Copy and download happen through browser APIs without a server upload.
Result passport
Every run reports its tool mode, timestamp and input/output size so transformed data can be audited.