Web Code Validator and Formatter

A web code validator and formatter checks pasted or uploaded HTML, CSS, JavaScript, or YAML for common syntax and structure issues, then formats or minifies the result. Live validation rechecks code after each change, and accessibility checks catch practical issues such as missing alt text and skipped heading levels.

Validation modes, HTML, JavaScript, CSS, and YAML, set which rule set applies, and code arrives either pasted into the editor or dropped as a file. Live validation rechecks after every change, with an adjustable debounce interval, and accessibility checks flag missing alt, missing lang, unassociated labels, and heading order gaps. Format standardizes indentation and spacing; minify compresses the code where it is safe to do so; the result copies to the clipboard or downloads as a cleaned file for deployment.

The core validation logic behind each mode is plain enough to restate directly:

• HTML: duplicate IDs are detected; unexpected closing tags are flagged; unclosed tags are flagged using a stack-based check; <html lang> is required when accessibility checks are on.
• CSS: braces are counted; semicolons are required inside rule blocks; unmatched {} raises an error.
• JavaScript: parsing is attempted via the Function constructor; a failure reports its line and column; script or module source type is respected.
• YAML: tabs are forbidden; indentation must be 2 spaces; key: value pairs are validated; comments starting with # are allowed.

Keyboard shortcuts cover the same actions: Ctrl+Enter validates, Ctrl+. toggles live validation, Ctrl+D downloads, Ctrl+Shift+C copies, Ctrl+/ toggles JS comments, and Ctrl+Alt+A toggles accessibility checks.

Development, education, and QA workflows all benefit from raised code quality and less review friction. Third-party snippets validate before integration. Rough drafts from prototypes clean up quickly. Style standardizes for handoffs and CI pipelines. Accessibility and SEO strengthen when basic a11y concerns are addressed early in the process.

• Pre-commit sanity checks: Validation and formatting run before a commit catch duplicate IDs, stray braces, or inconsistent YAML indentation.
• Code reviews and PR grooming: Normalized spacing and indentation keep review feedback focused on logic and architecture instead of style.
• Onboarding and teaching: Common HTML, CSS, JS, and YAML mistakes become visible in real time for students or junior developers.
• Content management and theming: Embedded widgets and theme overrides validated ahead of deployment prevent broken layouts and console errors.
• Ops and configuration: YAML configs for CI, CD, Kubernetes, or static site generators verified in advance avoid production incidents caused by bad whitespace.
• Accessibility and SEO hygiene: Missing alt text, missing lang, and heading order gaps, once surfaced, improve screen reader support and search crawl clarity.
• Performance passes: Safe assets minify into compact code for faster delivery while a formatted source copy stays on hand.
• Quick triage of bug reports: User-provided code pasted into the editor reproduces errors with caret pointers, turning a bug report into an actionable fix.