How to Check If Your Website Is Secure (A Developer's Guide)

"Is my website secure?" is a surprisingly difficult question to answer. Security isn't a binary state. There's no single checkbox that makes your site safe. But there is a practical set of checks that covers the most common and most exploitable issues in modern web applications.

This guide walks through what to check, how to check it, and what "secure enough" actually looks like for a web app in production.

What "secure" actually means

When security professionals assess a web application, they're looking at several layers. Each layer has its own risks and its own fixes.

Transport security is whether data between the browser and your server is encrypted. This is your SSL/TLS certificate, your HTTPS configuration, and your HSTS header.

Configuration security is whether your server is set up to resist common attacks. This includes security headers (CSP, X-Frame-Options, X-Content-Type-Options), CORS policy, cookie attributes, and DNS records.

Application security is whether your code is vulnerable to attacks like XSS, SQL injection, CSRF, and broken access control. This is the hardest layer to test automatically and the layer where the most serious vulnerabilities live.

Dependency security is whether the libraries and frameworks you use have known vulnerabilities. An outdated version of a popular library can be just as dangerous as a bug in your own code.

Infrastructure security is whether your server, hosting provider, and deployment pipeline are properly locked down. Exposed admin panels, default credentials, and open ports fall into this category.

A thorough security assessment covers all five layers. For most developers, starting with transport and configuration security gives you the highest return for the lowest effort.

Transport security: SSL/TLS

Check that your site serves a valid SSL/TLS certificate, supports modern TLS versions (TLS 1.2 and 1.3), doesn't support deprecated protocols (SSLv3, TLS 1.0, TLS 1.1), uses strong cipher suites, and has HSTS enabled.

You can check your certificate in the browser by clicking the padlock icon in the address bar. For a deeper analysis, run your domain through an online SSL checker.

The most common issue is missing HSTS. Your site might use HTTPS, but without the Strict-Transport-Security header, a user's first visit might happen over HTTP before being redirected. That first unencrypted request is enough for an attacker on the same network to intercept.

Configuration security: headers and cookies

Open your browser dev tools, go to the Network tab, reload the page, and click the main document request. Check the response headers for:

Content-Security-Policy: controls where scripts, styles, and resources can load from. Missing on most sites.

Strict-Transport-Security: forces HTTPS. Should have a long max-age (at least one year).

X-Content-Type-Options: should be set to nosniff. Prevents MIME type sniffing.

X-Frame-Options: should be DENY or SAMEORIGIN. Prevents clickjacking.

Referrer-Policy: should be strict-origin-when-cross-origin. Prevents URL leakage.

Permissions-Policy: disables browser APIs you don't use (camera, microphone, geolocation).

Then check your cookies in the Application tab. Every session cookie should have HttpOnly, Secure, and SameSite attributes set.

Application security: the harder stuff

Automated tools can check for some application-level issues:

Reflected XSS: does user input appear in the page without escaping?

SQL injection: do error messages reveal database queries when special characters are submitted?

Open redirects: does your app redirect to user-supplied URLs without validation?

Exposed secrets: are API keys, database credentials, or tokens visible in page source or JavaScript bundles?

For business logic vulnerabilities (can user A access user B's data? can someone skip the payment step?), automated scanning won't help. You need manual testing or a professional penetration test.

DNS and email security

If your domain sends email (transactional emails, notifications, password resets), check your DNS records:

SPF: lists which servers can send email from your domain.

DKIM: cryptographically signs outgoing emails.

DMARC: tells receiving servers what to do with emails that fail SPF/DKIM checks.

Missing email security records mean anyone can send emails that appear to come from your domain. This is a phishing risk for your users and can damage your domain's email reputation.

Dependency security

Run npm audit (Node.js) or pip audit (Python) to check for known vulnerabilities in your dependencies. Not every vulnerability is exploitable in your specific context, but critical and high severity issues in dependencies that handle user input, authentication, or network requests should be addressed.

A practical checklist

Before shipping, verify these ten things:

Valid SSL certificate with auto-renewal configured
HSTS header with max-age of at least one year
Content-Security-Policy header set
X-Content-Type-Options set to nosniff
X-Frame-Options set to DENY
Session cookies have HttpOnly, Secure, and SameSite
CORS policy uses an explicit allowlist, not wildcard with credentials
SPF, DKIM, and DMARC records configured
No secrets or API keys in page source or JavaScript bundles
Dependencies checked for known vulnerabilities

Automated checking

You can check most of the items above manually using browser dev tools and command-line DNS lookups. If you want to do it faster, run your URL through Hexora at hexora.uk. It checks all the externally visible items (SSL, headers, CORS, cookies, DNS, secrets, technology fingerprinting) in under 15 seconds and tells you exactly what to fix.

For the application-level and dependency checks, you'll need to test those separately using your own tools and code review.

Secure enough

Perfect security doesn't exist. But covering the fundamentals listed above puts you ahead of the vast majority of web applications on the internet. These aren't advanced techniques. They're configuration settings that take minutes to implement and protect every user who visits your site.

Start with the checklist. Fix the easy things first. Then decide whether your application warrants deeper testing.