SEO Analyzer - Free On-Page SEO Checker Tool

How Does the SEO Analyzer Work?

This SEO analyzer works by parsing the raw HTML source code you provide and running a series of checks against SEO best practices. Here is the process:

1. HTML Parsing: The tool creates a DOM parser from your pasted HTML, the same way a browser would. This allows it to query specific elements like title tags, meta elements, headings, and images.
2. Meta Tag Extraction: It extracts the title tag content and measures its length, reads the meta description and checks character count, looks for meta keywords, canonical URL, and robots directives.
3. Heading Analysis: It maps the entire heading hierarchy (H1 through H6), checks for the presence of exactly one H1, verifies proper nesting order, and flags skipped levels.
4. Image Audit: Every img element is checked for an alt attribute. Images without alt text are flagged as errors since they hurt both accessibility and image SEO.
5. Link Analysis: Internal and external links are counted separately. The tool checks for the presence of links (pages without any links are flagged) and distinguishes between link types.
6. Social Tag Verification: Open Graph and Twitter Card meta tags are checked for completeness — title, description, image, and type attributes. If your social tags are incomplete, you can fix them with the Open Graph generator and then re-analyze.
7. Scoring: Each check is weighted and scored. Passed checks earn full points, warnings earn partial points, and errors earn zero. The final score is a percentage of total possible points.

All analysis runs entirely in your browser using the DOMParser API. No HTML is sent to any server, making this tool safe for analyzing confidential or unpublished pages. For a deeper dive into what each meta tag does and why it matters, read our SEO meta tags guide.

Benefits of Using an SEO Analyzer

Practical Use Cases

An on-page SEO checker is useful across a wide range of workflows. Here are the most common scenarios where this tool adds real value:

• Pre-Publish QA: Before publishing a new blog post or landing page, run the HTML through the analyzer to make sure no SEO basics are missing — a missing meta description alone can cost you click-through rate.
• Client Audits: SEO agencies can quickly audit client pages and generate shareable reports showing exactly what needs to be fixed, without needing access to the client's CMS.
• Template Validation: After building a new website template, check that all pages it generates include proper meta tags, headings, and social tags before the template goes live.
• Competitor Comparison: View the source of a competitor's top-ranking page, paste it into the analyzer, and see how their on-page SEO compares to yours — you might find patterns worth replicating.
• Developer Handoff: Use the report as a checklist for developers to ensure every SEO requirement is implemented before deployment. Pair it with a keyword density check for a more complete content audit.
• Content Management: Editors can verify that content management systems are outputting correct meta tags and heading structures for each published page, catching template bugs early.

How to Use This SEO Analyzer

Getting an SEO report takes less than a minute. Here is the step-by-step process:

1. Get Your HTML Source: Open the webpage you want to analyze in your browser. Right-click and select "View Page Source" (or press Ctrl+U / Cmd+U). Select all text (Ctrl+A) and copy it (Ctrl+C).
2. Paste the Code: Paste the copied HTML into the input area on the left panel of this tool. You can also click the Paste button for quick clipboard access.
3. Click Analyze: Press the "Analyze SEO" button. The tool will parse your HTML and run all checks instantly — no waiting for server-side processing.
4. Review Your Score: The large score ring shows your overall SEO health. Green (80+) is excellent, yellow (60-79) is good, orange (40-59) needs work, and red (below 40) requires significant fixes.
5. Check Each Item: Scroll through the results list. Each check shows a pass, warning, or error status with a specific recommendation for fixing any issues found.
6. Filter by Category: Use the category filter buttons (Meta Tags, Content, Images, Links, Social, Technical) to focus on specific areas of your page's SEO.
7. Review Detailed Findings: Below the main checks, the detailed findings section shows extracted values like your actual title text, description, heading structure, and more.
8. Fix and Re-Analyze: After making changes, paste the updated HTML and run the analyzer again to confirm your score improved. If you need to build new meta tags from scratch, try the meta tag generator to create them quickly.

Why I Built This Tool

I kept running into the same problem: I would finish building a page, deploy it, and then realize I forgot the meta description or the H1 was missing. By that point, catching the mistake meant either opening DevTools and manually checking each tag or paying for an SEO tool that wanted access to my entire site. Neither option felt right for a quick, one-page check.

So I built this analyzer. You paste the HTML, you get a score, you see exactly what is wrong, and you fix it. No account, no site verification, no data leaving your browser. I use it before every launch now, and I added the sample HTML buttons so people who are learning SEO can see what a good page looks like versus a bad one.

If it saves you from shipping a page with a missing title tag, it did its job. And if you find it helpful, sharing it with a colleague or on social media is the best way to support it.

Frequently Asked Questions