How it Works
A full website health report in under 90 seconds - here is exactly what happens when you submit a URL.
The process
Five steps from URL to PDF
Step 1
Enter your URL
Paste any publicly accessible web address into the scan form. No account required for the free scan. Paid plans let you queue multiple domains and set up scheduled monthly re-scans.
Step 2
We run 20 checks across six categories
Our scanner fetches your page, inspects HTTP headers, parses the HTML, checks meta tags, tests HTTPS configuration, measures image sizes, validates accessibility attributes, and more. A full Lighthouse browser render then follows for the Performance score - that render is the part that takes the most time.
Step 3
Results in under 90 seconds
You see an instant estimate for most categories while Lighthouse finishes its browser-based audit in the background. The final score is real Lighthouse data - the same engine Chrome DevTools uses - not an approximation.
Step 4
Receive a clean PDF report by email
Once the scan is complete, we generate a branded PDF report and send it to your email address. Agency-tier clients receive white-labelled reports ready to forward directly to their clients - no Nel404 branding visible.
Step 5
Fix findings using our guidance
Each flagged issue includes a plain-English explanation and a recommended fix. On scheduled-scan plans, re-scans automatically track whether scores improve month-on-month, giving you a clear record of progress to show clients.
What we check
Category breakdown
| Category | What we look at |
|---|---|
| Performance | Page load time, Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS), First Contentful Paint (FCP), Total Blocking Time (TBT), image compression, render-blocking resources, server response time |
| SEO | Title tag, meta description, heading hierarchy (H1–H3), canonical URL, robots.txt, sitemap presence, structured data (JSON-LD), mobile-friendliness signals, link text quality |
| Security | HTTPS enforcement, mixed content, HTTP security headers (CSP, HSTS, X-Frame-Options, X-Content-Type-Options, Referrer-Policy), cookie Secure + HttpOnly + SameSite flags, outdated library detection |
| Accessibility | Image alt attributes, colour contrast ratio (WCAG AA), form label associations, ARIA landmark roles, keyboard navigation, focus visibility, skip-to-content links |
| Mobile | Viewport meta tag, tap target sizes (minimum 48×48 px), font sizes (minimum 12 px), horizontal scroll, mobile-specific resource hints |
| Best Practices | Deprecated HTML/JS APIs, console errors, HTTPS redirects from HTTP, browser compatibility, doctype presence, charset declaration, cross-origin link safety |
See it in action
Run a free scan on any public URL - no account needed. Results in under 90 seconds.
Run a free scan now