Enter your data or use the example, then run the tool.
Worked example
JavaScript tokens are colored while the image-looking string stays literal text. Switch languages to compare grammars.
Method
highlight.js uses only the selected registered grammar; auto-detection is disabled. Escaped span output is additionally cleaned with DOMPurify and shown in a scriptless sandbox. HTML export contains local styling/CSP.
Limits
Code ≤50,000 characters; nine listed grammars. Highlighting is not formatting, validation or execution. Pathological grammar input can hit the 2.5-second worker deadline. No external theme/font/CDN.
All work stays in this browser. Each disposable worker is terminated after 2.5 seconds or cancellation. Inputs and processing logs are not sent to analytics.
Sanitized HTML ≤1 million characters / 10,000 elements / depth 50. No links, images or active content are retained.
Your inputs stay on this device. Only optional, consented page visits are measured. Input values, files, filenames and processing logs are not sent to Analytics.
When switching languages, text, settings and selected files are temporarily kept on this device. Transfers are removed after restoring; interrupted transfers are cleaned up on a later visit. Inputs and files are never uploaded.