Stack playbook · Snapshot 23 October 2026
Next.js on Fastly: readiness playbook
What 108 measured sites on this stack get right, where they fall short, and the Next.js on Fastly-specific steps that close each gap.
- Sites measured
- 108
- Median readiness index
- 75/100
- Profiles on this stack
- 81
detected from homepage HTML and headers
all sites: 64
top-50K sites
Readiness by lane
Enable
87/100
All sites 77
Harden
67/100
All sites 56
Accelerate
69/100
All sites 64
Recover
9/100
All sites 10
The Next.js on Fastly playbook
Gaps ordered by impact, with the platform-specific step where one exists.
Modern image formats in use
32% 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.
On Next.js: The next/image component serves optimized formats automatically.
Guide: AVIF, WebP, JPEG, and PNG: Choose the Right Image Format
security.txt published
12% observed · all sites 7.1%
Publish /.well-known/security.txt with at least Contact and Expires fields, as RFC 9116 requires, and review it before it expires.
CAA records limit who can issue certificates
14% observed · all sites 13%
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.
No render-blocking scripts in <head>
31% observed · all sites 48%
Add defer to scripts that need the DOM, async to independent ones such as analytics, or move them to the end of the body.
On Next.js: Use the next/script component with an appropriate loading strategy.
Guide: Control Third-Party Scripts Before They Control Your Page
HTTP/3 advertised
30% observed · all sites 37%
Turn on HTTP/3 at your CDN. Browsers fall back to HTTP/2 automatically, so the risk is low.
DNSSEC signed
6.5% observed · all sites 8%
Enable DNSSEC at your DNS provider, then add the DS record at your registrar. Plan provider moves carefully: a stale DS record can make the domain fail to resolve.
Guide: Website Uptime Readiness: Prepare Before Traffic Arrives
HSTS kept for at least a year
72% observed · all sites 34%
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.
On Next.js: Add the header in the headers() option of next.config.js for all routes.
On Fastly: Add the header in VCL or a header rule as described in Fastly's HSTS guide.
Nameservers spread across providers
9.3% observed · all sites 10%
Treat this as an advanced step. Add a secondary DNS provider through zone transfers or a multi-provider setup, then test changes carefully, since both providers must stay in sync.
Guide: Website Uptime Readiness: Prepare Before Traffic Arrives
Where Next.js on Fastly sites lead
- DMARC policy enforces quarantine or reject87% observedall sites 39%
- HSTS kept for at least a year72% observedall sites 34%
- Static files cached for 30 days or more83% observedall sites 51%
- Content Security Policy present63% observedall sites 32%