How to fix hsts max age too short on Shopify

Steps for Shopify

1. Shopify automatically handles HTTPS and HSTS for all storefronts — you cannot directly edit server response headers from the Shopify admin.
2. Shopify's CDN (Fastly) sets HSTS on your behalf. If a scanner reports a short max-age, it may be reading a header injected by a third-party app or a custom Shopify Storefront/Hydrogen deployment.
3. Check your installed apps (Admin → Apps) for any 'Security Headers', 'HTTP Headers', or 'CSP Manager' apps that may be overriding the HSTS header with a short max-age, and update or remove them.
4. If you use Shopify Plus with a custom domain proxy or a headless front-end (Hydrogen/Oxygen), set the header at the Oxygen edge or your own CDN layer — see the Headless / Custom entry below.
5. For Shopify-managed stores with no custom proxy, no action is required; Shopify's platform-level header is already compliant. Re-run the scan to confirm.

What is hsts max age too short?

HTTP Strict Transport Security (HSTS) is a security header your web server sends to browsers that says: "Only ever connect to this site over HTTPS — never plain HTTP." The `max-age` value inside that header tells the browser how many seconds to remember and enforce that rule. A value of 86400 means just one day — after 24 hours the browser forgets the instruction and could allow an unencrypted HTTP connection again. The industry standard is 31536000 (one full year), meaning the browser stays protected for 365 days after each visit.

A short max-age creates a real window of vulnerability every single day. If a visitor's browser cache expires and they visit your store over an insecure network (coffee shop Wi-Fi, hotel hotspot), an attacker can intercept that initial unencrypted HTTP request and steal login credentials, session cookies, or payment data — a classic SSL-stripping attack. Beyond security, Google has used HTTPS as a ranking signal since 2014 and continues to favor sites that implement it properly; a misconfigured HSTS header signals to security-aware crawlers and auditors that your HTTPS setup is incomplete. Short max-age values are also explicitly flagged by OWASP and browser preload-list requirements, and many enterprise buyers and compliance frameworks (PCI-DSS, SOC 2) require HSTS to be set correctly before approving a vendor.

See the complete Hsts max age too short guide for every platform and the full background.