How to fix missing strict transport security on BigCommerce

Steps for BigCommerce

1. BigCommerce manages the underlying infrastructure and automatically sends HSTS headers for storefronts on *.bigcommerce.com and SSL-enabled custom domains.
2. In your BigCommerce Admin go to Store Setup → Store Profile and ensure your custom domain has an active SSL certificate (BigCommerce provisions this automatically via Let's Encrypt).
3. If you are using a custom CDN or reverse proxy (e.g., Cloudflare) in front of BigCommerce, configure HSTS as a custom response header in your CDN dashboard.
4. For Cloudflare: SSL/TLS → Edge Certificates → Enable HSTS → set Max-Age to 12 months, enable 'Apply HSTS policy to subdomains'.
5. Verify with DevTools as described above.

Strict-Transport-Security: max-age=31536000; includeSubDomains

What is missing strict transport security?

HTTP Strict-Transport-Security (HSTS) is a security header your web server sends to browsers to say: "Always use HTTPS when talking to this site — never plain HTTP." Once a browser sees this header, it will automatically upgrade any future HTTP requests to HTTPS for the duration you specify (the `max-age`, measured in seconds). Without it, a visitor who types your domain or follows an old HTTP link could briefly connect over an unencrypted connection before being redirected, which is a window an attacker can exploit.

Without HSTS, your store is vulnerable to SSL-stripping attacks, where an attacker on the same network (e.g., a coffee shop Wi-Fi) intercepts the first unencrypted HTTP request before your redirect kicks in, silently reading or tampering with the connection. This can expose customer login credentials, payment data, and session cookies — creating serious legal risk under GDPR, CCPA, and PCI-DSS. Google also uses HTTPS as a ranking signal; a missing HSTS header signals an incomplete security posture that can reduce trust scores. Perhaps most directly, browsers increasingly warn users about mixed or insecure connections, and a visible browser security warning will kill conversions instantly.

See the complete Missing strict transport security guide for every platform and the full background.