Technical SEO is where development and search visibility meet. You can have great content, but if your site is slow, unstructured, or hard for search engines to crawl, you’ll struggle to rank.

This checklist is designed specifically for developers working with PHP, Symfony, Drupal, or any modern web stack.

1. Site Speed & Performance

Performance is a ranking factor and directly impacts user experience.

Checklist:

• Use HTTP/2 or HTTP/3
• Enable compression (Gzip or Brotli)
• Minify CSS, JS, and HTML
• Optimize images (WebP/AVIF)
• Implement lazy loading
• Reduce server response time (TTFB)
• Use a CDN

Developer Tip:

Use caching aggressively:

• Symfony → HTTP cache / reverse proxy
• Drupal → built-in caching layers

2. Core Web Vitals

Google measures real user experience using:

• Largest Contentful Paint (LCP) → loading speed
• Interaction to Next Paint (INP) → responsiveness
• Cumulative Layout Shift (CLS) → visual stability

Checklist:

• Avoid large render-blocking resources
• Preload critical assets
• Set width/height on images
• Avoid layout shifts from dynamic content

3. Crawlability & Indexing

If search engines can't crawl your site properly, nothing else matters.

Checklist:

• Ensure all important pages return 200 status codes
• Fix broken links (404s)
• Use a clean robots.txt file
• Submit XML sitemap
• Avoid orphan pages (pages with no internal links)

Developer Tip:

Make sure your routing system (Symfony/Drupal) produces:

• Clean URLs
• No duplicate paths

4. URL Structure

URLs should be simple, readable, and consistent.

Checklist:

• Use hyphens (not underscores)
• Keep URLs short and descriptive
• Avoid query-heavy URLs when possible
• Use canonical tags to prevent duplicates

Example:
✔ /technical-seo-checklist
✖ /index.php?id=123&cat=seo

5. HTML Structure & Semantics

Search engines rely heavily on clean HTML.

Checklist:

• One <h1> per page
• Proper heading hierarchy (h1 → h2 → h3)
• Use semantic elements (<article>, <section>, <nav>)
• Add alt text to all images
• Ensure proper meta tags (title, description)

6. Mobile-Friendliness

Google uses mobile-first indexing.

Checklist:

• Responsive design (CSS media queries)
• Avoid horizontal scrolling
• Ensure tap targets are usable
• Optimize font sizes and spacing

7. HTTPS & Security

Security is a ranking signal and builds trust.

Checklist:

• Force HTTPS (301 redirect)
• Fix mixed content issues
• Use secure cookies
• Implement proper headers:
  • Content-Security-Policy
  • X-Frame-Options
  • X-Content-Type-Options

8. Redirects & Status Codes

Incorrect redirects can kill SEO performance.

Checklist:

• Use 301 for permanent redirects
• Avoid redirect chains
• Avoid redirect loops
• Use 410 for permanently removed content

9. Structured Data (Schema Markup)

Helps search engines understand your content.

Checklist:

• Add JSON-LD structured data
• Use schema types:
  • Article
  • Product
  • FAQ
• Validate using structured data testing tools

10. Duplicate Content Control

Duplicate content confuses search engines.

Checklist:

• Use canonical tags
• Avoid duplicate routes
• Normalize trailing slashes
• Handle www vs non-www properly

11. Log Files & Monitoring

Developers often overlook this—but it’s powerful.

Checklist:

• Analyze server logs
• Identify crawl frequency
• Detect crawl errors
• Monitor bot behavior

12. JavaScript SEO

If your frontend relies on JS, be careful.

Checklist:

• Ensure server-side rendering (SSR) or hydration
• Avoid blocking content behind JS
• Test with JavaScript disabled
• Use progressive enhancement

13. Internal Linking

Structure matters for SEO.

Checklist:

• Link related content
• Use descriptive anchor text
• Avoid deep page nesting (>3 clicks)
• Ensure important pages get more internal links

14. CMS / Framework-Specific Tips

Symfony:

• Use proper routing (no duplicate routes)
• Implement caching (HTTP cache, Varnish)
• Generate dynamic sitemaps

Drupal:

• Use SEO modules (Metatag, Pathauto)
• Optimize caching layers
• Clean URL aliases

PHP (general):

• Avoid unnecessary database queries
• Optimize backend performance
• Use opcode caching (OPcache)

15. Testing & Tools

Before and after deploying changes:

Checklist:

• Test with Lighthouse
• Use search console for indexing issues
• Validate structured data
• Monitor performance regularly

Final Thoughts

Technical SEO isn’t a one-time task—it’s an ongoing process. The best developers treat SEO as part of the architecture, not an afterthought.

If you implement even 70–80% of this checklist, your site will already outperform a large portion of competitors.

Pro Tip

Turn this checklist into:

• A reusable internal audit tool
• Automated tests in your CI/CD pipeline
• A service offering (if you want to monetize)