# Fast OG > Preview and diagnose Open Graph, Twitter Card, and social sharing metadata before links go live. ## Topic Hubs - [Guides](https://fastog.dev/blog): Open Graph and social preview debugging guides ## Guides & Articles - [Diagnostic Rules](https://fastog.dev/data-sources): Rule sources, heuristics, and verification notes for Fast OG diagnostics - [OG Debugging Checklist Before Launch](https://fastog.dev/og-debugging-checklist): A practical checklist for checking Open Graph, Twitter Card, canonical URL, and image delivery before sharing a page. - [Social Image Delivery Risks](https://fastog.dev/social-image-delivery-risks): How redirects, signed URLs, mixed content, wrong content types, and oversized images break social sharing cards. - [Metadata Conflicts That Break Sharing Previews](https://fastog.dev/metadata-conflicts): Learn why canonical URL, og:url, final URL, duplicate tags, and JavaScript-injected metadata can make platform previews unpredictable. - [Crawler-visible metadata: what social bots actually read](https://fastog.dev/crawler-visible-metadata): Understand why Open Graph and Twitter Card tags must be present in the first HTML response, not only after JavaScript hydration. - [Refreshing stale social previews after a fix](https://fastog.dev/social-cache-refresh): A practical guide to clearing platform caches when Facebook, X, LinkedIn, or chat apps keep showing old titles and images. - [OG image requirements for reliable link cards](https://fastog.dev/og-image-specs): Recommended dimensions, formats, content types, redirects, and CDN behavior for Open Graph images that render consistently. ## Tools - [OG Analyzer Results](https://fastog.dev/result): Review social preview metadata, image delivery, and platform diagnostics for a submitted URL ## Main - [Home](https://fastog.dev/): Fast OG homepage ## About & Legal - [Privacy Policy](https://fastog.dev/privacy): What Fast OG collects and how URL diagnostics are handled - [Terms of Service](https://fastog.dev/terms): Terms for using Fast OG - [Security](https://fastog.dev/security): Security practices, SSRF protections, and responsible reporting - [FAQ](https://fastog.dev/faq): Answers to common questions about social preview diagnostics - [Platform Rules](https://fastog.dev/compatibility): Platform limitations and preview approximation notes - [About](https://fastog.dev/about): About Fast OG Full context: https://fastog.dev/llms-full.txt Sitemap: https://fastog.dev/sitemap.xml