ABOUT THE PROJECT
A focused workspace for testing web ideas
HTML Online Viewer was created to make previewing, debugging and sharing a self-contained web page feel immediate—without accounts, uploads or a complicated development environment.
Why we built it
Many online editors are either too limited for real troubleshooting or too crowded for a quick experiment. This viewer keeps the source and result side by side, preserves the preview position while you edit, and puts practical tools such as validation, formatting, minification and responsive testing close at hand.
Privacy by design
Your working HTML, optional CSS and optional JavaScript are stored locally in your browser. The editor does not require an account and does not upload your draft code to our servers. The preview runs inside a sandboxed frame to reduce unintended access to the surrounding site.
How tools are reviewed
The HTMLOnline editorial and engineering team maintains the explanations, examples and browser implementations together. Important releases run automated transformation checks, invalid-input tests, production builds and critical desktop and mobile browser journeys before publication.
Every tool page identifies whether ordinary processing stays in the browser or uses an optional cloud renderer, includes practical limitations, and shows its latest review date. Automated output can still have edge cases, so we explain what should be checked before replacing an original file or publishing a result.
What the viewer is for
Experiment with HTML structure, CSS styles and JavaScript behavior while seeing the result instantly.
Use line markers, parsing feedback and preview console messages to locate common problems.
Format code for readability, compare minified size and export a single portable HTML file.
Start with one file
The default example keeps its markup, styles and behavior inside index.html. Separate CSS and JavaScript tabs remain available when a project grows.