TL;DR: HTTP security headers are a simple but effective way to harden your website against common attacks like XSS, clickjacking, and code injection. This post explains the key headers -- X-Frame-Options, X-XSS-Protection, Content-Security-Policy, Referrer-Policy, and more -- with a practical example of configuring them in a Netlify _headers file. You can check your current score at securityheaders.com and aim for an A rating.

How To Use Security Headers

With HTTP response headers, you can harden your website security and also prevent/mitigate attacks

Thanks to HTTP security headers, it is possible to be a few steps ahead, ensuring the security of our sites, our users and our data

HTTP security headers protect you against the types of attacks that your site is most likely to come across. These headers protect against XSS, code injection, clickjacking, etc.

You can check the score for your websites headers on below site. https://securityheaders.com/

If you have A in the score, then you are doing good. For other scores securityheaders will suggest what things can be added.

Example

For hosting my site on netlify I have added headers as below

[[headers]]
  for = "/*"

  [headers.values]
    X-Frame-Options = "DENY"
    X-XSS-Protection = "1; mode=block"
    Content-Security-Policy = "script-src 'self'"
    Referrer-Policy = "same-origin"
    Permissions-Policy = "fullscreen=(), geolocation=()"
    X-Content-Type-Options = "nosniff"

    cache-control = '''
    max-age=0,
    no-cache,
    no-store,
    must-revalidate'''

Some important headers to set are Content-Security-Policy, Permissions-Policy, Referrer-Policy, Strict-Transport-Security More explanation can Additional Information section at https://securityheaders.com/

Result

This is the score after adding all required security headers