Write or paste your code
Type into the HTML, CSS and JS boxes, paste a whole page into the HTML box, start from a template with New, or open files, a folder or a zip with Open.
WebLabFree Online HTML, CSS and JS Editor
Write HTML, CSS and JavaScript with a live page beside your code, a console and saved projects, then minify or format HTML, CSS, JavaScript, JSON and SVG, one file or a whole website folder, with nothing uploaded.
Live editor
HTML
CSS
JSmodule
Ln 1, Col 1
The page has stopped answering. An endless loop may be running.
Minify
Language
How far
Indent
Your code
Minified
Working
Many files at once
Drop a whole website folder, a zip or a few files. Every HTML, CSS, JavaScript, JSON and SVG file is minified or formatted; everything else is copied as it is, so you get the full site back in one zip.
Drop files, a folder or a zip here
A zip is opened and its files listed. Up to 5,000 files or 500 MB at once. Nothing leaves this browser.
| File | Kind | Size | After | Smaller by | Done | Actions |
|---|
Keys while you use the tool: Ctrl Enter runs the page or minifies, Shift Alt F formats, Ctrl S keeps the project, F3 finds and ? shows help. Nothing you type or open leaves this browser.
How to Use WebLab
Watch the page
The page beside the code updates as you type. Pick a phone, tablet or laptop size above it, turn it sideways, or show the page on its own.
Read the console
Logs, warnings and errors appear under the page. Click a line number to jump to it in the code, and type JavaScript at the bottom to run it in the page.
Keep and share
Your project is kept in this browser once you change it. Save as gives one HTML file or a zip of separate files, and Share makes a link with the code inside it.
Minify or format
In Minify or Format, paste code or open a file, choose the language or let the tool tell, pick the level or the indent, and copy or download the result with its sizes.
Do a whole site
In Many files, drop a website folder or a zip. Every code file is minified or formatted, the rest is copied, and you download it all as one zip with the folders kept.
Why Use WebLab?
⚡ A live page as you type
The page runs beside your code and updates after a short pause; CSS changes apply at once without a reload, and the page keeps its scroll position while you work.
📱 Every screen size
See the page as a 360 or 412 pixel phone, a tablet, a laptop, a full HD screen or a size of your own, scaled to fit, so a layout can be checked without a second device.
🧯 Safe from endless loops
A loop that runs for more than two seconds is stopped and named in the console, and a page that stops answering can be stopped with one button, so a typing slip never freezes the tool.
🗜️ Minify with numbers
See the size before and after, the gzip size a server would send, what was changed (comments, colours, quotes, tags) and how long it took, with source maps for JavaScript.
🧹 Readable code again
Format HTML, CSS, SCSS, Less, JavaScript, JSX, TypeScript, JSON and Vue with your indent and line length, also code that was minified, and undo it with Ctrl+Z in the live editor.
🔒 Nothing uploaded
There is no account and no upload. Your code, projects and files stay in this browser, and your page runs in a closed-off frame that cannot reach this site or other tools.
HTML, CSS and JavaScript Explained
🧱 Three languages, one page
HTML gives a page its content and structure, CSS its look and layout, and JavaScript its behaviour. WebLab keeps them in three boxes and joins them into one page, or into one file or a zip of three when you save.
🗜️ What minifying removes
Browsers ignore comments, most spaces and line breaks, and many quotes and closing tags. Minifying removes them and shortens colours, numbers and JavaScript names, so the file is smaller and loads faster while the page stays the same.
📏 Why gzip matters
Most web servers compress files with gzip or a similar method before sending them. The gzip size is closer to what a visitor actually downloads, so it shows how much minifying really saves on top of that compression.
Frequently Asked Questions
Is WebLab free, and is my code uploaded?
It is free, with no registration. Like every page on ZeroDataUpload, it is supported by advertising. Your code is run, minified and formatted in this browser and is never sent to a server. Your projects and settings are kept in this browser once you change something, so they are still there next time.
Can the code I run here reach this site or my data?
No. Your page runs in a closed-off frame that does not share this site's address, so it cannot read this site's storage, its cookies or the data of other tools. A page that uses localStorage gets a separate one, kept with the project. Files your own code links to, such as a font or a script on another website, load only inside that frame and only because you wrote the link.
What does minifying change, and is it safe?
Gentle removes comments and spaces. Balanced also shortens colours, numbers and quotes and joins CSS rules that sit together. Smallest also drops optional closing tags. Each change keeps what the page shows and does; Smallest may stop the code passing a validator. Keep your original files: minified code is for publishing, not for editing.
Which languages can it format?
HTML, CSS, SCSS, Less, JavaScript, JSX, TypeScript, JSON and Vue files, with your choice of indent (2 spaces, 4 spaces or tabs), line length, quotes, semicolons and trailing commas. Formatting also turns minified code back into something readable.
What happens if my code has an endless loop?
A loop that keeps running for more than two seconds is stopped, and the console names its line, so a slip such as i-- instead of i++ does not freeze the page. If the page stops answering for another reason, a Stop it button appears over the preview.
How big can projects and files be?
Up to 100 projects are kept in this browser, 1,000,000 characters together, because every tool on the site shares the same storage; bigger work can be saved as a file. Minify and Format open files up to 30 MB, and Many files takes up to 5,000 files or 500 MB at once.
How is WebLab different from CodeForge?
CodeForge converts data from one format to another, such as JSON to CSV, XML or YAML, and can give JSON pretty or minified as part of that. WebLab is for web pages: you write and run HTML, CSS and JavaScript, and it minifies or formats them, as well as JSON and SVG, one file or a whole folder.