Free Online HTML Tools
Format, validate, view, minify, and convert HTML. All 16 tools run client-side — your data never leaves your browser.
Beautify and format HTML markup with proper indentation.
Pretty print HTML for improved readability.
Check HTML markup for common syntax and structure issues.
Preview and inspect HTML in a live rendered view.
Edit HTML with syntax highlighting and live preview.
Beautify and format JavaScript embedded in HTML.
Minify HTML by removing whitespace and comments.
Convert Jade/Pug templates to standard HTML.
Convert HTML markup to Jade/Pug template syntax.
Convert Excel spreadsheet data to an HTML table.
Format Vue.js Single File Components — template, script, style.
Format Angular templates with structural directives (*ngIf, *ngFor).
Format Babel-transpiled JavaScript output for debugging.
Format Markdown with embedded JSX components.
Format Glimmer.js / Ember Handlebars templates.
Format Salesforce Lightning Web Components templates.
What Are Online HTML Tools?
HTML tools help web developers format, validate, preview, convert, and minify HTML markup. Whether you are debugging a layout issue, cleaning up auto-generated code, or converting between template languages like Jade/Pug and HTML, these tools save time and catch errors early.
All tools on this page run entirely in your browser — no uploads, no accounts, no latency. Paste your HTML and get instant results.
Common Use Cases
- check_circleFormat minified HTML from a CMS or build tool output
- check_circleValidate HTML structure before submitting to W3C standards
- check_circlePreview rendered HTML in a live viewer without a browser tab
- check_circleMinify HTML templates to reduce page load size
- check_circleConvert Jade/Pug templates to plain HTML for deployment
- check_circleConvert HTML markup back to Jade for template-based projects
- check_circleTransform Excel spreadsheet data to HTML tables
Frequently Asked Questions
What is the difference between an HTML formatter and a minifier?
A formatter adds indentation and line breaks to make HTML readable. A minifier removes all whitespace and comments to reduce file size for production deployments.
What is Jade / Pug?
Jade (now called Pug) is an HTML template engine that uses indentation-based syntax instead of closing tags, making templates shorter and more readable during development.
Does the HTML validator check against W3C standards?
Our validator checks for common HTML syntax issues like unclosed tags, missing attributes, and structural errors. For full W3C compliance testing, the official W3C validator is recommended.
Can I preview HTML with CSS and JavaScript?
Our HTML viewer renders the markup in a sandboxed preview. For full interactive previews including external CSS and JS, a dedicated tool like CodePen may be more suitable.
Developer Insights
From the Blog
The Case for 100% Client-Side Data Processing
Why we built OpenFormatter to process all data locally, and what that means for your workflow security.
Why JSON Formatting Matters More Than You Think
How proper JSON structure prevents production bugs, improves debugging, and makes code reviews faster.
URL Encoding in JavaScript: encodeURI vs encodeURIComponent
A practical guide to the four URL encoding functions in JavaScript with real code examples.