Technical SEO Checklist for Developers: 47 Things to Check Before Launch

Why Developers Need to Care About Technical SEO

You build features. You ship code. SEO is the marketing team's problem, right?

Not anymore. The line between web development and SEO has blurred significantly. Core Web Vitals are ranking factors. JavaScript rendering affects indexing. Schema markup improves click-through rates. The decisions you make in code directly impact whether a site shows up in search results.

This checklist covers everything technical that affects SEO. Use it before launching a new site, after major updates, or as a quarterly audit. I have organized it by category so you can tackle one section at a time.

Crawlability: Can Search Engines Access Your Pages?

1. robots.txt Configuration

Your robots.txt file tells search engines what they can and cannot crawl. One wrong line can block your entire site from being indexed.

Check these:

File exists at yourdomain.com/robots.txt

No accidental Disallow: / blocking everything

Important directories are not blocked

Sitemap URL is referenced

User-agent rules are correct

Common mistake: Blocking /api/ is fine, but accidentally blocking /app/ or /pages/ can hide your content from Google.

2. Meta Robots Tags

These HTML tags control indexing at the page level. They override robots.txt permissions.

Add a meta tag with name="robots" and content="noindex, nofollow" to prevent indexing. Use content="index, nofollow" to allow indexing but block link following.

Check: Search for "noindex" in your codebase. Make sure it only appears on pages that should not be indexed (login pages, thank you pages, staging environments).

3. X-Robots-Tag Headers

The HTTP header version of meta robots. Often set at the server level and forgotten. The header looks like: X-Robots-Tag: noindex

Check: Use browser dev tools or curl to inspect headers on key pages. Look for any X-Robots-Tag headers.

4. HTTP Status Codes

Correct status codes tell search engines how to treat your pages.

200: Page exists, index it

301: Permanently moved, transfer rankings to new URL

302: Temporarily moved, keep the original URL indexed

404: Page not found, remove from index

410: Gone permanently, remove faster than 404

500: Server error, try again later

Check: Run your site through BulkAudit or use a crawler to identify pages returning unexpected status codes.

5. Redirect Chains

Multiple redirects in sequence slow down crawling and dilute link equity.

Bad: A redirects to B redirects to C redirects to D (3 redirects)

Good: A redirects directly to D (1 redirect)

Check: Test your key pages and old URLs. If you find chains longer than 2 hops, consolidate them.

6. Redirect Loops

A redirects to B, B redirects to A. Neither page can be crawled.

Check: Test all redirects. Your browser will show "too many redirects" error if loops exist.

Indexing: Will Search Engines Store Your Pages?

7. XML Sitemap

Your sitemap tells search engines which pages exist and when they were updated.

Requirements:

Located at /sitemap.xml (or referenced in robots.txt)

Contains only indexable, canonical URLs

No more than 50,000 URLs per sitemap

File size under 50MB uncompressed

lastmod dates are accurate (not just today's date for everything)

Check: Validate your sitemap at xml-sitemaps.com or in Google Search Console.

8. Canonical Tags

Canonical tags tell search engines which version of a page is the "official" one. Add a link element with rel="canonical" and the full URL as the href.

Check these:

Every page has a canonical tag

Canonical URLs are absolute, not relative

Canonical points to the correct URL (watch for http vs https, www vs non-www, trailing slashes)

Paginated pages have appropriate canonicals

Filtered/sorted pages canonicalize to the main version

9. Duplicate Content

Multiple URLs with the same content confuse search engines and split ranking signals.

Common causes:

www and non-www versions

http and https versions

Trailing slash and non-trailing slash

URL parameters creating duplicate pages

Print-friendly page versions

Session IDs in URLs

Fix: Pick one canonical version and redirect all others to it.

10. Pagination

For paginated content (blog archives, product listings), tell search engines how pages relate.

Modern approach: Use self-referencing canonicals on each page. Let Google figure out the relationship.

Avoid: rel="prev" and rel="next" are deprecated by Google.

11. Hreflang Tags

For multi-language or multi-region sites, hreflang tells search engines which version to show users. Add link elements with rel="alternate" and hreflang attributes for each language version, plus x-default for the fallback.

Check:

Every language version references all other versions

Include x-default for the fallback

Language codes are correct (en-us, not en_US)

URLs are absolute

Site Architecture: Is Your Site Easy to Navigate?

12. URL Structure

Clean URLs are easier for users and search engines to understand.

Good: /products/running-shoes/

Bad: /index.php?cat=12&product=456&session=abc123

Best practices:

Use lowercase letters

Use hyphens, not underscores

Keep URLs short but descriptive

Include target keywords naturally

Avoid unnecessary parameters

13. Site Depth

Important pages should be reachable within 3-4 clicks from the homepage.

Check: Create a visual sitemap or use a crawler to identify pages that are too deep in the hierarchy.

14. Internal Linking

Internal links distribute page authority and help search engines discover content.

Check:

Important pages have multiple internal links pointing to them

Anchor text is descriptive (not "click here")

No orphan pages (pages with no internal links)

Broken internal links are fixed

15. Breadcrumbs

Breadcrumbs help users and search engines understand site hierarchy. Example: Home > Products > Shoes > Running Shoes

Implementation: Use structured data (BreadcrumbList schema) alongside visible breadcrumbs.

16. Navigation

Your main navigation should be crawlable HTML links, not JavaScript-only menus.

Check: Disable JavaScript and verify navigation still works. Search engines may not execute complex JavaScript menus.

Page Speed: Core Web Vitals

17. Largest Contentful Paint (LCP)

Measures when the largest visible element loads. Target: under 2.5 seconds.

Common fixes:

Optimize hero images

Preload critical resources

Use a CDN

Reduce server response time

18. Cumulative Layout Shift (CLS)

Measures visual stability. Target: under 0.1.

Common fixes:

Set explicit dimensions on images and videos

Reserve space for ads and embeds

Avoid inserting content above existing content

Use CSS aspect-ratio or width/height attributes

19. Interaction to Next Paint (INP)

Measures responsiveness to user interactions. Target: under 200ms.

Common fixes:

Break up long JavaScript tasks

Reduce main thread blocking

Use web workers for heavy computations

Optimize event handlers

20. First Contentful Paint (FCP)

When first content appears. Target: under 1.8 seconds.

Common fixes:

Eliminate render-blocking resources

Inline critical CSS

Defer non-critical JavaScript

Optimize server response time

21. Time to First Byte (TTFB)

Server response time. Target: under 800ms.

Common fixes:

Use a CDN

Optimize database queries

Enable server-side caching

Upgrade hosting if needed

Images and Media

22. Image Format

Use modern formats for smaller file sizes.

Recommendation: WebP or AVIF with fallbacks for older browsers. Use the picture element with source elements for AVIF and WebP, plus an img fallback for JPEG.

23. Image Compression

Compress images without visible quality loss.

Tools: Squoosh, ImageOptim, or automated build pipelines.

24. Responsive Images

Serve appropriately sized images for each device. Use srcset and sizes attributes on img elements to let the browser choose the right image size.

25. Lazy Loading

Load images only when they enter the viewport. Add loading="lazy" to img elements.

Note: Do not lazy load above-the-fold images. They should load immediately.

26. Image Alt Text

Alt text helps search engines understand images and improves accessibility.

Good: "Red Nike running shoes on white background"

Bad: "image1.jpg" or "shoe" or empty alt

27. Video Optimization

Host on dedicated platforms (YouTube, Vimeo) for better performance

Use video sitemaps for Google to index video content

Provide transcripts for accessibility and SEO

Use poster images for faster initial page load

Mobile Optimization

28. Responsive Design

Site should work on all screen sizes without horizontal scrolling.

Check: Test on actual devices, not just browser dev tools. Real-world performance varies.

29. Mobile Viewport

Required meta tag for proper mobile rendering. Add a meta tag with name="viewport" and content="width=device-width, initial-scale=1".

30. Touch Targets

Buttons and links should be at least 48x48 pixels with adequate spacing.

Check: Run Lighthouse accessibility audit. It flags small touch targets.

31. Font Size

Text should be readable without zooming. Minimum 16px for body text.

32. No Intrusive Interstitials

Full-screen popups that block content can trigger Google penalties.

Allowed: Cookie consent banners, age verification (where legally required), small banners that do not block content.

Structured Data

33. Organization Schema

Tell search engines about your business using JSON-LD structured data with @type "Organization", including name, url, and logo.

34. Breadcrumb Schema

Enhance breadcrumbs in search results with BreadcrumbList structured data.

35. Article Schema

For blog posts and news articles.

36. Product Schema

For e-commerce product pages. Can enable rich results with price, availability, ratings.

37. FAQ Schema

For FAQ sections. Can dramatically increase SERP real estate.

38. Local Business Schema

For businesses with physical locations. Critical for local SEO.

39. Schema Validation

Check: Use Google's Rich Results Test to validate all structured data.

Security and HTTPS

40. HTTPS Everywhere

Every page should load over HTTPS. No mixed content.

Check:

Certificate is valid and not expired

No pages accessible via HTTP (should redirect to HTTPS)

No mixed content warnings (HTTP resources on HTTPS pages)

HSTS header is set for extra security

41. Security Headers

Important headers for site security: Strict-Transport-Security, X-Content-Type-Options: nosniff, and X-Frame-Options: DENY.

JavaScript and SEO

42. Server-Side Rendering

Content rendered by JavaScript may not be indexed properly. Use SSR or static generation for important content.

Check: View page source (not inspect element). If your content is not in the HTML, search engines may not see it.

43. Hydration Issues

When client-side JavaScript replaces server-rendered content incorrectly, it can cause indexing problems.

Check: Compare server-rendered HTML to what Google sees in Search Console's URL Inspection tool.

44. JavaScript Errors

Console errors can prevent page content from rendering.

Check: Test pages in Google Search Console's URL Inspection tool. It shows how Google sees your page.

45. Critical JavaScript

Ensure essential functionality works even if JavaScript fails to load.

Check: Disable JavaScript and verify key content is still visible.

International SEO

46. Country Targeting

In Google Search Console, set geographic target if your site serves a specific country.

47. URL Structure for International Sites

Three common approaches:

ccTLDs: example.de, example.fr

Subdomains: de.example.com, fr.example.com

Subdirectories: example.com/de/, example.com/fr/

Recommendation: Subdirectories are easiest to manage and consolidate domain authority.

Pre-Launch Checklist Summary

Before launching any site, verify:

Crawlability: robots.txt is correct, no accidental noindex tags, status codes are correct, no redirect chains or loops.

Indexing: XML sitemap is valid and submitted, canonical tags are correct, no duplicate content issues, hreflang is correct if applicable.

Architecture: URLs are clean and logical, important pages are within 3-4 clicks, internal linking is solid, navigation is crawlable.

Performance: LCP under 2.5s, CLS under 0.1, INP under 200ms, images are optimized.

Mobile: Responsive design works, touch targets are adequate, no intrusive popups.

Structured Data: Organization schema present, page-specific schema implemented, validated with Rich Results Test.

Security: HTTPS on all pages, no mixed content, security headers set.

How to Audit Technical SEO Quickly

Running through this entire checklist manually takes hours. Here is a faster approach:

Run BulkAudit on your key pages. This catches most technical issues automatically.

Check Google Search Console. The Coverage report shows indexing problems. Core Web Vitals report shows performance issues.

Use browser dev tools. Network tab shows resource loading. Lighthouse tab runs a quick audit.

Validate structured data. Google's Rich Results Test takes 30 seconds per page.

Test on real devices. Emulators miss real-world performance issues.

Technical SEO is not glamorous, but it is foundational. A site with perfect content will fail if search engines cannot crawl, index, and render it properly. Use this checklist to make sure the technical foundation is solid, then focus on content and links.