BigCommerce: readiness playbook

Readiness by lane

The BigCommerce playbook

Gaps ordered by impact, with the platform-specific step where one exists.

1. Static files cached for 30 days or more

   9.9% observed · all sites 50%

   Give versioned (fingerprinted) CSS, JavaScript, fonts and images Cache-Control: public, max-age=31536000, immutable, and change the file name whenever the content changes.

   Guide: Browser Caching Guide for Website Owners

2. HSTS kept for at least a year

   24% observed · all sites 31%

   Send Strict-Transport-Security on HTTPS responses. Start with a short max-age (for example 300 seconds), confirm every subdomain works over HTTPS, then raise it in steps to 31536000. Add includeSubDomains only when all subdomains are HTTPS. HSTS preload is optional and hard to undo; hstspreload.org itself does not recommend it by default.

   Guide: HTTPS and TLS Guide for Website Owners

3. No render-blocking scripts in <head>

   8% observed · all sites 44%

   Add defer to scripts that need the DOM, async to independent ones such as analytics, or move them to the end of the body.

   Guide: Control Third-Party Scripts Before They Control Your Page

4. Modern image formats in use

   25% observed · all sites 40%

   Serve WebP or AVIF with a JPEG or PNG fallback, either through an image CDN or by generating both formats at build time.

   Guide: AVIF, WebP, JPEG, and PNG: Choose the Right Image Format

5. security.txt published

   2% observed · all sites 5.5%

   Publish /.well-known/security.txt with at least Contact and Expires fields, as RFC 9116 requires, and review it before it expires.

   Guide: A Practical Website Health Check for Owners

6. DMARC policy enforces quarantine or reject

   37% observed · all sites 31%

   Publish DMARC with p=none and a reporting address first, fix any legitimate senders that fail SPF or DKIM alignment, then move to quarantine and finally reject.

   Guide: A Practical Website Health Check for Owners

7. CAA records limit who can issue certificates

   6.8% observed · all sites 11%

   Publish CAA records naming every CA you actually use, including the CAs your CDN uses for managed certificates. Add an iodef contact if you want reports.

   Guide: HTTPS and TLS Guide for Website Owners

8. Content Security Policy present

   12% observed · all sites 31%

   Start with Content-Security-Policy-Report-Only to see what would break, tighten the policy over a few weeks, then enforce it.

   Guide: Payment Security and PCI DSS: What Website Owners Need to Know

Where BigCommerce sites lead

• X-Content-Type-Options: nosniff95% observedall sites 48%
• HTTP/3 advertised82% observedall sites 36%
• Canonical URL declared96% observedall sites 70%
• robots.txt published>99% observedall sites 79%

A note on hosted platforms

On BigCommerce, the platform controls much of the TLS, header and caching configuration. Owners mostly influence content-level checks such as images, structured data, social previews and the sitemap. Header-level gaps are worth raising with the platform.

All 31 checks on BigCommerce

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