Stack playbook · Snapshot 23 October 2026
Next.js on Vercel: readiness playbook
What 331 measured sites on this stack get right, where they fall short, and the Next.js on Vercel-specific steps that close each gap.
- Sites measured
- 331
- Median readiness index
- 74/100
- Profiles on this stack
- 148
detected from homepage HTML and headers
all sites: 64
top-50K sites
Readiness by lane
Enable
86/100
All sites 77
Harden
70/100
All sites 56
Accelerate
73/100
All sites 64
Recover
4/100
All sites 10
The Next.js on Vercel playbook
Gaps ordered by impact, with the platform-specific step where one exists.
No render-blocking scripts in <head>
26% 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
Modern image formats in use
42% 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.
On Vercel: Vercel Image Optimization serves modern formats.
Guide: AVIF, WebP, JPEG, and PNG: Choose the Right Image Format
security.txt published
14% 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.
HTTP/3 advertised
18% 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
9.4% 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
Content Security Policy present
35% observed · all sites 32%
Start with Content-Security-Policy-Report-Only to see what would break, tighten the policy over a few weeks, then enforce it.
On Next.js: Next.js documents nonce-based CSP with middleware.
Guide: Payment Security and PCI DSS: What Website Owners Need to Know
DMARC policy enforces quarantine or reject
57% observed · all sites 39%
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.
CAA records limit who can issue certificates
45% 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.
Where Next.js on Vercel sites lead
- HSTS kept for at least a year97% observedall sites 34%
- Static files cached for 30 days or more98% observedall sites 51%
- Offscreen images lazy-loaded97% observedall sites 62%
- CAA records limit who can issue certificates45% observedall sites 13%