G11 — Chapter 7 - Technical SEO

Criterion G11: Gzip/Brotli Compression — guide + checklist

PART 1 - Fundamentals Chapter 7 - Technical SEO Keyword : compression gzip/brotli

This criterion seems “simple”, but it creates many discrepancies in production.

Criterion G11 — Gzip/Brotli Compression is part of our SEO checklist (335 criteria). Here, you have a practical method to check and fix it — with a concrete example.

What exactly this criterion covers

This criterion seems “simple”, but it creates many discrepancies in production.

G11 — Gzip/Brotli Compression (Chapter 7 - Technical SEO): Server compression for HTML, CSS, JS, reducing size by 70-90%

Why it matters (SEO + UX)

Why it matters: it is a comprehension signal for the engine. When poorly applied, we often observe: ambiguity (wrong associated request), duplication between pages, or performance loss on Core Web Vitals.

On volume-generated sites, this criterion also acts as a safeguard: a stable rule prevents 1,000 errors at once.

How to check (step by step)

Approach: express audit (manual + 1 tool). Recommended tool: Chrome DevTools Network.

  1. Open the page in Chrome → DevTools → Performance/Network tab.
  2. Run Lighthouse and note the main weak point.
  3. Check if the problem repeats on “money” pages.

Tip: first isolate 10 representative URLs (top pages + generated pages) before scaling the fix.

How to fix properly

Strategy: make a “clean” fix (no patch), then measure.

  • Fix the biggest cost source (images, JS, fonts, cache).
  • Retest, then apply to the template (not page by page).
  • Add a safeguard: weight budget (KB) and CI check if possible.

Then: recrawl 50–200 URLs, then monitor Search Console for 7–14 days (impressions/CTR/indexing).

Concrete example (illustrative)

Example (illustrative):

  • Context: blog article for B2B SaaS in Nice
  • Before: Lighthouse: 44/100 (heavy JS, unoptimized images).
  • After: Lighthouse: 76/100 (lazy-load, compression, cache).
  • Note: Goal: stabilize LCP.

Checklist to tick

  • [ ] Measure before/after
  • [ ] Respect: 70% reduction
  • [ ] Improvement on template
  • [ ] No CWV regression
  • [ ] Cache and compression OK
FAQ

Frequently asked questions — G11

What is the most common mistake on “Gzip/Brotli Compression”?

Fixing an isolated page without fixing the template/import: the error returns on the next generation.

Which tool is the fastest to check at scale?

For this type of criterion, a crawl (e.g. Screaming Frog) plus a targeted check in Chrome DevTools Network is generally the fastest combo.

How to prevent this from happening on 10K generated pages?

Freeze an auto-generation rule (title/structure/schema/URLs) plus add an automatic control (crawl or test) before production import.

Ready to go from theory to action?

Validate this criterion with an audit, then deepen the method in the Academy.

Audit with the tool → Learn in the Academy →