Website Code Checker
Drop in a page’s files or a zip. One fix plan for the HTML, CSS, JavaScript and images, and smaller files back.
- Free, no sign-up
- Files never leave your computer
- Up to 10 MB
Drop a zip, a folder or files here
A page’s HTML with the CSS and JavaScript it loads (images and fonts too, if you like). Up to 10 MB and 400 files.
Your files stay on your computer. They’re read in this browser tab and never uploaded to us, so it’s fine to check code that isn’t live yet.
Reads HTML, CSS, JavaScript, images and fonts: errors, unused CSS, old or doubled libraries, debug code and heavy files.
For the best results
- Upload the page with what it loads: the .html file plus its CSS and JavaScript. A zip of the site folder works best, because links between the files then match up.
- Add every type of page you have (home, a service page, a blog post). Unused CSS is measured against the pages you upload, so more page types give a truer number.
- Saving a page from the browser (Ctrl+S, "Webpage, complete") gives you the HTML and its files in one folder. Choose that folder here.
- Start with the steps marked high impact, then download the minified files and test them on a copy of the site first.
- For the SEO, AI search and accessibility side of a page, press "Full SEO, AI and accessibility check" next to it.
Mistakes to avoid
- Deleting CSS just because it shows as unused here: menus, other pages and scripts may need it.
- Replacing live files without keeping the originals.
- Uploading node_modules or build folders (they're skipped anyway).
Free on this page, or in the free app
| On this page | In the RR SEO Tools app | |
|---|---|---|
| Use the tool | Free, no sign-up | Free account (just your email) |
| Full reports | A preview, then the full report when you sign in free | Always shown in full |
| Check pages by URL | 10 free a day with an account | The same free allowance |
| Your reports | Shown on this page | Saved to your account to reopen and compare |
| Phone and computer | Works in any browser | Install it like an app |
| Every tool | One tool per page | All tools, one sign-in and one history |
Open this tool in the app Free. Sign in with just your email.
Check the files behind a page, before or after they go live
Online checkers look at a live page. This one looks at the files themselves: the HTML, the stylesheets, the scripts, the images and fonts, exactly as they are on your computer. That makes it useful for a site that isn't live yet, a theme you're about to install, a developer's handover, or a folder you saved from the browser.
Nothing is uploaded. The files are read in your browser tab and stay on your computer.
What it checks
- Pages: tags not closed properly, duplicate IDs, missing title, description, H1, language or viewport, a stray noindex, broken structured data, form fields and buttons screen readers can't name, images without sizes, render-blocking scripts and files loaded over http.
- Stylesheets: the rules none of your uploaded pages use, @import chains, fonts without font-display, piles of !important, duplicate selectors and old prefixes.
- Scripts: syntax errors, old jQuery with known security holes, libraries included twice, development builds, Moment.js, leftover console.log and debugger lines, document.write and requests that freeze the page.
- Images and fonts: heavy images, images far bigger than they're shown, and fonts that could be WOFF2.
Everything goes into one fix plan, the most important and quickest first, and you can download every file minified, in a zip with the same folders.
How to use this tool
- 1Drop in the files
A zip of the site folder, the folder itself, or a page's HTML with its CSS and JavaScript. Up to 10 MB.
- 2Read the plan
Start with "Do these first". Each step says what was found, in which file, why it matters and what to do.
- 3Download the smaller files
One by one or all in a zip with the same folder structure. Test them on a copy of the site first.
- 4Check a page in depth
Send any page to the Full Page Check for 60+ SEO, AI search and accessibility checks.
Frequently asked questions
Are my files uploaded anywhere?
No. They're read by your browser and never sent to us, so you can check code that isn't public yet. Only if you press "Full SEO, AI and accessibility check" is that one page's HTML sent to the Full Page Check.
How do I get the files of a live page?
In Chrome or Edge, open the page and press Ctrl+S (Cmd+S on a Mac), then choose "Webpage, complete". You get the HTML and a folder with its files. Choose both here. For a whole theme, zip its folder.
Is the minified JavaScript safe to use?
It's made with Terser, the minifier most build tools use, which shortens names and removes spaces and comments without changing what the code does. Still, test on a copy of the site and keep the originals.
Why does it say some CSS is unused when the site needs it?
Unused means no uploaded page matches the rule. Menus that open on a click, other pages and content added by scripts can still use it. Upload more page types for a truer number, and test before removing anything.
Can it check PHP or WordPress theme files?
It reads .php files as pages, but PHP tags aren't run, so the result is rough. For a WordPress site, save a finished page from the browser instead, or use the HTML & CSS Analyzer on the live page.
Is it free?
Yes, with no sign-up.
Get help beyond the tool
Speed and Core Web Vitals Rescue fixes what slows your site at the source, from heavy scripts to images, and proves it with a before-and-after report.
Part of the free technical SEO tools · See all free tools
© 2026 RR Web Services. This free tool, its code and its methodology are proprietary. You may not copy, reproduce or reuse any part of it without our written permission.