Open SEO Crawler vs Semrush

Open SEO Crawler is a free, self-hosted, open-source tool for auditing websites for technical SEO issues. It checks titles, meta descriptions, H1s, canonicals, structured data, redirects, HTTP errors, indexability, hreflang, mobile viewports, mixed content, images and security headers. It detects numerous CMS platforms, including Shopify, WordPress, Webflow, Wix, Squarespace, Kajabi, Ghost, Drupal, HubSpot and Joomla, then applies crawl recommendations. Optional Playwright rendering supports JavaScript-heavy sites, while compare mode identifies content absent from raw HTML.

Bulk reports can be exported to XLSX, and sitemap export is available. Default settings allow 1,500 pages, five workers, a 0.4-second per-host delay and depth 10; the page cap can be changed to unlimited. The crawler runs locally without accounts, telemetry or API calls, though it contacts target sites and checks GitHub for updates when requested. Installers are documented for Linux, macOS 11 or newer, and Windows 10/11. The project uses the MIT license.

Semrush has no write-up on Specifiction yet; its figures are above.