Check SEO Onpage

Check SEO Onpage audits the on-page SEO of any page you're viewing, right in your browser. Click the icon to get an A–F score with a clear list of errors and how to fix them. 10 GROUPS OF CHECKS: • Basic meta: title, description, canonical, robots, viewport, charset, lang • Heading structure H1–H6 (exactly one H1, no skipped levels) • Content: word count, text/HTML ratio, sentence and paragraph length • Images: missing alt attributes • Links: internal/external, nofollow, anchor text • Social: Open Graph, Twitter Card • Structured data: JSON-LD schema.org with required-field validation • Technical: HTTPS, hreflang, mixed content, robots.txt, sitemap, broken links • Target keyword: keyword in title/H1/URL/alt and density • Core Web Vitals: LCP, CLS, INP TOOLS: • Google SERP preview with pixel-accurate truncation • Highlight images missing alt and the heading structure directly on the page • Heading outline — click to jump to any heading • Score history with a trend chart • Ignore a check per website so it no longer counts toward the score • Keyboard shortcuts: Alt+Shift+S opens the popup, Alt+Shift+D toggles the panel • Optional AI suggestions for title & meta description using your own Anthropic API key • Export reports to JSON, CSV or PDF • English and Vietnamese interface PRIVACY FIRST: All analysis runs locally in your browser. The extension only asks for network access to the site you're viewing, and only when you click "Network check". The optional AI feature is off by default and only sends data when you add your own API key and click "Generate".