Type your domain followed by /robots.txt into any browser address bar (example.com/robots.txt). If the file exists, you'll see plain text directives that tell search engine crawlers which parts of your site they can or cannot access. If you get a 404 error, your site has no robots.txt file. For a quick validity check, paste the URL into Google Search Console under Index > Robots.txt Tester. This tool shows you exactly what Google sees and flags syntax errors that could accidentally block important pages. It also lets you test specific URLs against your rules to confirm crawlers can reach them. At Ottawa SEO, we run this test after every robots.txt change because one misplaced slash can block your entire site from indexing. Common things to verify when reviewing your robots.txt: - User-agent directives match your intent (Googlebot, Bingbot, or * for all crawlers) - Disallow rules aren't accidentally blocking critical pages like your homepage, category pages, or XML sitemap - Sitemap location is declared at the bottom (Sitemap: https://yourdomain.com/sitemap.xml) - No conflicting rules that allow and block the same path - File size stays under 500 KB—Google ignores anything larger You can also use third-party crawlers like Screaming Frog or Sitebulb, which parse your robots.txt automatically and show which URLs would be blocked during a crawl. This catches issues before they hurt rankings. WordPress users should check that SEO plugins (Yoast, Rank Math) aren't generating duplicate or conflicting robots.txt rules through both the plugin and a physical file. Only one should exist. If you're managing 20+ domains like we do in our portfolio, spot-check robots.txt quarterly—CMS updates and plugin changes sometimes rewrite these files without warning. Most sites need only 5–10 lines. If yours exceeds 50 lines, you're probably overcomplicating it or blocking content better handled through noindex meta tags.