# Open Graph Preview > An Open Graph preview shows the link card your page will produce on X, LinkedIn, Slack, Facebook and iMessage before you post it. It reads the og:title, og:description and og:image tags from the live page and renders the card exactly as those platforms will. Source: https://rankcert.com/tools/open-graph-preview Free, no signup. Updated: 2026-08-29 ## How to use it 1. Paste the URL you are about to share. 2. We read its Open Graph and Twitter card tags. 3. Compare the rendered preview against what you expected, then add any missing tags. ## Questions ### What size should an og:image be? 1200 x 630 pixels, under 8MB, served over https. That ratio renders as a large card everywhere; anything smaller than 600 x 315 falls back to a small thumbnail. ### Why does my link still show the old image? Every platform caches Open Graph data. Use the platform's own debugger (Facebook Sharing Debugger, LinkedIn Post Inspector) to force a re-scrape after you change the tags. ### Do I need Twitter tags if I already have Open Graph? X falls back to og: tags, so you mostly need twitter:card set to summary_large_image. The other twitter: tags only matter if you want different copy on X. ### Does an og:image affect SEO? Not directly. It affects click-through on shared links, which is where its value is. ### Which Open Graph tags are required? og:title, og:type, og:image and og:url are the four in the specification. In practice og:description matters too, because most platforms show it under the title. ### Why does Slack show a card but LinkedIn does not? Each platform has its own crawler and its own cache. LinkedIn requires the image to be reachable without a redirect and at least 1200 x 627; Slack is far more forgiving. Run the LinkedIn Post Inspector to see its exact complaint. ### Can I use a different image per platform? Yes, via twitter:image for X and og:image for everything else, but it is rarely worth maintaining two. One 1200 x 630 image serves every platform well. ### Does the image need absolute URLs? Yes. Relative paths in og:image fail on most crawlers. Always use a full https:// URL. ## Related tools - [robots.txt Generator](https://rankcert.com/tools/robots-txt-generator): Build a valid robots.txt with your disallow rules, sitemap reference and optional AI crawler blocks, ready to paste at the root of your site. - [llms.txt Generator](https://rankcert.com/tools/llms-txt-generator): Generate an llms.txt file that tells AI answer engines what your product is and which pages matter, in the markdown format the proposal specifies. - [Schema Markup Generator](https://rankcert.com/tools/schema-markup-generator): Generate valid JSON-LD for Organization, SoftwareApplication, Article and BreadcrumbList, ready to paste into your page head. - [FAQ Schema Generator](https://rankcert.com/tools/faq-schema-generator): Turn a list of questions and answers into valid FAQPage JSON-LD, the structured data AI answer engines quote most readily. - [Meta Tags Checker](https://rankcert.com/tools/meta-tags-checker): Check any page's title, meta description, canonical, robots and heading structure, and see the exact issues that hurt its rankings. - [SEO Checker](https://rankcert.com/tools/seo-checker): Run eleven on-page checks against any URL: title, description, canonical, headings, alt text, Open Graph, word count and indexability, with the exact fixes.