Best Free Technical SEO, Schema & HTTP Header Audit Tools (2026)

Catching broken canonicals, invalid JSON-LD, hreflang mismatches, or CORS misconfigurations before deployment prevents costly indexing and API regressions.

1

Technical SEO, JSON-LD, Sitemap & Robots.txt Studio

Deep on-page HTML SEO auditor, 10-type JSON-LD builder/validator, BCP-47 hreflang, and RFC 9309 robots.txt

FreeNo account
  • Deep HTML heading/meta/schema audit
  • Sitemap dedupe, validator & splitter
  • BCP-47 reciprocal hreflang generator
Try it free
2

HTTP Headers, CORS Linter, CSP & cURL Studio

Shell-aware cURL-to-code transpiler, redirect loop detector, CORS preflight linter, and CSP builder

FreeNo account
  • 6-language cURL code transpiler
  • CORS & Content-Security-Policy linter
  • HTTP status & cache header reference
Try it free

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