SEO

Technical SEO Checklist: 15 Things Your Developer Should Fix

September 10, 2025 · 2 min read

Technical SEO Checklist: 15 Things Your Developer Should Fix

SEO Is a Technical Problem

Most agencies treat SEO as a marketing exercise. We treat it as an engineering problem. The foundation of every successful SEO strategy is a technically sound website — and most websites have fixable technical issues holding them back.

Here are 15 things your developer should check and fix:

Core Web Vitals

1. Largest Contentful Paint (LCP) Under 2.5s

LCP measures how fast your main content loads. Fix it by preloading hero images, using proper image formats (WebP/AVIF), implementing lazy loading below the fold, and minimizing render-blocking CSS.

2. Cumulative Layout Shift (CLS) Under 0.1

CLS measures visual stability. Fix it by setting explicit width/height on images and videos, reserving space for dynamic content, and avoiding injecting content above existing content after page load.

3. Interaction to Next Paint (INP) Under 200ms

INP measures responsiveness. Fix it by breaking up long JavaScript tasks, deferring non-critical scripts, and minimizing main-thread blocking.

Crawling & Indexing

4. Clean Robots.txt

Don’t block important resources. Don’t set unnecessary crawl delays. Reference your sitemap. Keep it simple.

5. XML Sitemap That’s Accurate

Your sitemap should include every page you want indexed and nothing else. No 404s, no redirects, no noindexed pages. Update lastmod dates only when content actually changes.

6. Proper Canonical Tags

Every page should have a self-referencing canonical tag. This prevents duplicate content issues from URL parameters, www vs non-www, and trailing slashes.

7. No Orphan Pages

Every important page should be reachable through internal links. If it’s not in your navigation or linked from other content, search engines may not find it.

On-Page Technical

8. Proper Heading Hierarchy

One H1 per page. H2s for main sections. H3s for subsections. Don’t skip levels. This helps both search engines and screen readers understand your content structure.

9. Image Optimization

Descriptive alt text on every image. Proper file names (not IMG_3847.jpg). Compressed to appropriate sizes. Served in modern formats where supported.

10. HTTPS Everywhere

SSL certificate installed and all HTTP URLs redirecting to HTTPS. No mixed content warnings. HSTS headers configured.

11. Mobile-First Design

Google uses mobile-first indexing. Your mobile experience isn’t just important for users — it’s what Google sees first. Test every page at 375px width.

Performance

12. Preconnect to Third-Party Origins

Add <link rel="preconnect"> for fonts, analytics, and CDN origins. This saves 100-300ms per origin on first connection.

13. Font Loading Strategy

Use font-display: swap to prevent invisible text. Preload your primary font file. Consider system font stacks for body text.

14. Minimize JavaScript

Defer non-critical JavaScript. Remove unused scripts. Page builders are the #1 offender — a custom theme can cut JS payload by 80%.

15. Server Response Time Under 200ms

TTFB (Time to First Byte) should be under 200ms. If it’s slower, your hosting or server configuration needs attention. Good managed WordPress hosting solves this.

The Developer Advantage

This is why we approach SEO as developers first. Every item on this list is a code-level fix, not a marketing tactic. A technically sound site is the foundation everything else builds on.


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