Tools to validate your website

1. SSL and TLS
2. SSL Labs Server Test
3. Security headers
4. Security Headers and Mozilla Observatory
5. Performance
6. PageSpeed Insights, Lighthouse, and WebPageTest
7. Markup and standards
8. W3C validators
9. DNS and email
10. DNS and deliverability checkers
11. Turn results into a launch list
12. Let Rocketeers handle it

You can't fix what you can't see. After you've set up a server and put a site live, these free tools grade the things that matter — TLS, security headers, performance, and markup — and tell you exactly what to improve. Run them at launch, then again whenever you make a significant change.

#SSL and TLS

#SSL Labs Server Test

The gold standard for inspecting your HTTPS configuration. It grades your TLS setup from A+ down to F and flags weak protocols, missing chain certificates, and poor cipher choices.

• SSL Labs — aim for an A+; you can also run our own SSL checker; here's how to get there with Cloudflare.

A common failure it surfaces is an incomplete certificate chain. You can also check expiry yourself from the command line.

#Security headers

#Security Headers and Mozilla Observatory

These scan the HTTP response headers your site sends and grade them — whether you set Strict-Transport-Security, a Content Security Policy, X-Content-Type-Options, and so on.

• securityheaders.com — quick header grade (or use our security headers checker).
• Mozilla Observatory — a broader security scan.

More context in optimizing web application security.

#Performance

#PageSpeed Insights, Lighthouse, and WebPageTest

These measure how fast your site loads for real users and give specific, prioritized fixes — render-blocking resources, uncompressed assets, slow server response.

• PageSpeed Insights — Google's Core Web Vitals report.
• Lighthouse — built into Chrome DevTools, under the "Lighthouse" tab.
• WebPageTest — detailed waterfall from multiple locations.

If your server response is the bottleneck, it'll show up as a slow time to first byte. General wins are in optimizing website performance, and on the server side make sure you've enabled gzip compression.

#Markup and standards

#W3C validators

Catch broken HTML and invalid CSS that can cause subtle rendering and accessibility issues.

• W3C Markup Validator — HTML.
• W3C CSS Validator — CSS.

#DNS and email

#DNS and deliverability checkers

If you send email from your domain, verify your SPF, DKIM, and DMARC records so your mail isn't flagged as spam.

• MXToolbox — DNS, blacklist, and email record lookups.

See improving email deliverability for what those records should contain.

#Turn results into a launch list

Running the tools is step one; acting on them is step two. Pair this with the website launch checklist so nothing slips through before you go live.

#Let Rocketeers handle it

Most of what these tools flag — weak TLS, missing security headers, no compression, an expired certificate — comes down to server configuration. Rocketeers provisions servers and sites with strong TLS, sensible headers, and compression on by default, and monitors your sites after launch, so you spend your time fixing the few things left rather than the basics.