Technical SEO is the cornerstone of website rankings. No matter how high the quality of your content, if your website has technical issues, search engines may not be able to correctly crawl, index, or understand your pages, and your rankings will naturally suffer.
This article compiles 20 must-check on-site SEO items, covering crawl and indexing, page structure, technical optimization, and performance. You can use this checklist to systematically check and fix technical issues on your website.
Completion criteria for beginners: Don't try to fix every issue in the audit report at once. After reading this article, you should end up with a task list of no more than 5 items, each including the affected page, detection evidence, priority, person responsible for the change, and a review method.
Before you start: Website domain, 3-5 of the most important product or category pages, and whether GSC is already connected. For changes involving robots, canonical, redirects, and noindex, have a developer confirm the impact first—don’t publish in bulk directly.
I. Crawl and Indexing Issues (6 items)
1. robots.txt Configuration
Check that robots.txt is correctly configured and ensure no important pages are accidentally blocked.
2. Page Indexing Status
Use Google Search Console to check whether pages are correctly indexed.
3. Canonical tag
Ensure each page has only one canonical URL to avoid duplicate content issues.
4. Noindex tag
Check whether important pages have been incorrectly marked with noindex.
5. Submit sitemap
Ensure sitemap.xml has been submitted to Google Search Console.
6. Website crawl depth
Check the website structure to ensure important pages can be reached within 3-4 clicks.
II. Page Structure Issues (5 Items)
7. Title tag
Keep the length between 50-60 characters, include the core keyword, and avoid duplication.
8. Meta Description
Keep the length between 150-160 characters, attract clicks, and include the core keyword.
9. H1-H6 heading hierarchy
Each page has only one H1, with a clear and reasonable heading hierarchy.
10. Image optimization
Images have alt attributes, appropriate file sizes, and use WebP format.
11. Structured data
Add Schema.org structured data to help search engines understand the content.
III. Technical Optimization Issues (5 Items)
12. HTTPS configuration
The entire site uses HTTPS with no mixed content issues.
13. Mobile responsiveness
The website displays correctly on mobile devices without layout issues.
14. Page Speed
Use Core Web Vitals checks to optimize loading performance.
15. 404 Error Page
Configure a user-friendly 404 page that provides navigation and search functionality.
16. Redirect Configuration
Ensure 301 redirects are correct, with no redirect chains or loops.
4. Content and Link Issues (4 items)
17. Duplicate Content
Check whether the website has a large number of duplicate or similar content.
18. Page Intent and Topic Coverage
Check whether the page clearly addresses the target user's task, the content matches the title, and keyword stuffing is avoided.
19. Internal Link Structure
Reasonable internal links help users and search engines navigate.
20. External Link Quality
Check outbound links to ensure they point to high-quality, relevant websites.
5. How to Perform a Site SEO Audit
Method 1: Use SEO Agent for Automated Auditing
The simplest way is to use SEO Agent's site audit feature. You only need to enter the website URL, and the SEO Agent will automatically crawl the pages and generate a detailed audit report.
Note: In the SEO Agent dialog box, enter "Perform a site SEO audit for example.com and crawl 20 pages" to get a complete audit report.
Method 2: Manual Checks
- Check Google Search Console: Review indexing status, crawl errors, and coverage reports.
- Use Screaming Frog: Crawl the entire website and check status codes, titles, descriptions, canonical tags, etc.
- Check page performance: Use PageSpeed Insights or Lighthouse.
- Check mobile: Use Google's mobile-friendly test tool.
- Check structured data: Use Rich Results Test.
6. Recommended Fix Priorities
Based on the impact of the issues, we recommend fixing them in the following priority order:
| Priority | Issue Type | Impact | Fix Difficulty |
|---|---|---|---|
| 🔴 High | Pages not indexable, HTTPS issues, mobile responsiveness | Critical | Medium |
| 🟠 Medium | Page speed, duplicate content, canonical issues | Significant | Medium to high |
| 🟢 Low | Image optimization, structured data, robots.txt | Minor | Low |
💡 Practical tips: Use SEO Agent's site audit feature to quickly identify issues and generate a fix checklist. The Agent will sort by impact and provide priority recommendations, so you know which issues to fix first.
7. Frequently Asked Questions
Q1: How many pages does a site audit need to crawl?
For small websites (under 100 pages), we recommend crawling all pages. For large websites, start by crawling key pages (homepage, product pages, category pages, popular content pages), then gradually expand. SEO Agent crawls 20 pages by default and supports up to 100 pages.
Q2: How often should a site audit be performed?
We recommend a quick check once a month and a comprehensive audit once a quarter. If the website has a major redesign or content update, conduct an audit immediately.
Q3: Which is more important, technical SEO or content SEO?
Both are important, but technical SEO is the foundation. If technical issues are not resolved, even the best content cannot achieve good rankings. We recommend solving technical issues first, then optimizing content.
Q4: How do I check JavaScript-rendered content?
SEO Agent's site audit supports JavaScript rendering checks and can detect whether the content of a single-page application (SPA) can be correctly crawled by search engines.
8. Use Codex + SEO Agent to turn audit reports into a fix checklist
Don’t just look at “how many issues were found” the first time. First, have SEO Agent crawl representative samples of your homepage, key category pages, product pages, and content pages. Then have Codex sort them by whether they block crawling/indexing, affect page value, modification risk, and the number of pages affected.
Use SEO Agent to audit example.com, focusing on the homepage, core category pages, product pages, and blog samples.
Split the results into: P0 crawling/indexing blockers, P1 ranking and click issues on key pages, P2 experience and compliance issues. For each item, list the specific URL, evidence, fix action, possible risks, and recheck method.
Don’t treat every finding as a ranking issue, and don’t recommend bulk changes without keeping backups.Fix P0 issues first and recheck using the same URL. Then handle key pages that already have exposure or drive qualified inquiries. Before modifying canonical, redirects, robots, or noindex, confirm the purpose of the page to avoid accidentally removing valid pages. Once the audit tool identifies issues, GSC can help confirm Google’s actual crawling and indexing status.
9. Summary
Technical SEO audits are an ongoing process, not a one-time task. By regularly checking and fixing these technical issues, you can ensure your website is always in optimal condition and lay a solid foundation for content rankings.
Remember: Technical SEO solves the problem of “letting search engines find and understand your content,” while content SEO solves the problem of “making search engines believe your content deserves to rank.” Both are indispensable.
👉 Take action now: Use SEO Agent The site audit feature runs a comprehensive technical SEO check on your website and shows what issues need to be fixed.