Free Tool
On-Page SEO
Checker & Audit
70+ checks across 12 categories. Audit up to 100 URLs in one run — heatmap shows which categories fail across your whole site. Includes AEO readiness. No signup.
10,000+ pages analyzed
What gets checked
Length, keyword placement, uniqueness, truncation risk
Length, keyword presence, call-to-action, uniqueness
Length, readability, keyword inclusion, trailing slashes
H1 count, nesting order, keyword presence, length
Word count, reading level, keyword density, thin content signals
Author info, citations, trust signals, expertise markers
JSON-LD presence, types, required fields, nesting
Internal links, external links, anchor text, broken links
Alt text, file size, format, lazy loading, dimensions
Canonical tag, robots directives, sitemap hints
OG tags, Twitter cards, image dimensions, descriptions
Answer targets, featured snippet structure, voice search readiness
Paste up to 100 URLs — heatmap shows site-wide patterns across every category
Checks answer targeting, featured snippet structure, and AI search formatting — no other free checker includes this
Why this one
Most free tools check title, meta, and a handful of basics. Whistle runs 70+ checks across every on-page factor.
Title, meta, URL, headings, content quality, E-E-A-T, schema, links, images, canonicals, Open Graph, and AEO readiness.
Paste up to 100 URLs and audit all at once. The heatmap shows which categories fail across your entire site — missing schema on 40 pages is a process gap, not 40 individual fixes.
Checks if your pages are structured for AI search: answer targeting, featured snippet readiness, schema completeness, voice search formatting. No other free on-page checker includes this.
How it works
Paste any URL
Blog post, landing page, product page. Add an optional target keyword for deeper keyword-specific analysis.
70+ checks run instantly
12 categories scored individually: title tag, meta description, URL structure, headings, content quality, E-E-A-T signals, schema markup, links, images, canonicals, Open Graph, and AEO readiness.
Heatmap shows the pattern
Bulk results surface which categories fail across your whole site. Schema missing on 40 pages isn't 40 individual fixes — it's a broken template. Fix the process, every future page benefits.
FAQ
What is an on-page SEO checker?
An on-page SEO checker analyzes individual web pages for factors that affect search engine rankings — title tags, meta descriptions, heading structure, content quality, schema markup, internal links, and more. Unlike technical SEO audits (which check site speed, crawlability, and server config), on-page checkers focus on the content and structure of each page itself.
Can I check multiple URLs at once?
Yes. Paste multiple URLs (one per line) and the tool switches to bulk audit mode. You get a sortable table with scores for every page, a heatmap showing which categories fail most often, and expandable rows for the full per-page report. Bulk mode is where the tool is most useful — it surfaces patterns across your site, not just individual page issues.
Does the tool store my data?
No. The page is fetched, analyzed, and results are returned directly to your browser. Nothing is stored in a database. No signup is required to run an audit.
What is AEO and why does this checker include it?
AEO (Answer Engine Optimization) is the practice of structuring content so AI-powered search engines — ChatGPT, Perplexity, Google AI Overviews — understand and cite it. Most free audit tools check title tags and meta descriptions from 2018. Whistle includes AEO checks: structured content for direct answers, featured snippet readiness, schema completeness, and voice search formatting. No other free on-page checker includes this.
How is the score calculated?
Each of the 12 categories contributes a weighted portion to the final score (0 to 100). Title tags and content quality carry the most weight because they have the most direct SEO impact. The weights are based on correlation studies and search engine documentation.
What makes this different from SEOptimer or Seobility?
Three things. Depth: 70+ checks across 12 categories vs. the typical 15-20 checks across 3-4 categories. Bulk mode: audit up to 100 URLs in one run with a heatmap showing site-wide patterns — no other free checker does this. AEO readiness: checks for AI search optimization that none of the major free tools have added yet.
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