How to test Open Graph tags: Facebook Sharing Debugger, Twitter Card Validator, and more
Every major platform provides a debugger tool to test and refresh OG tags. The Facebook Sharing Debugger (developers.facebook.com/tools/debug) is the most important because it also refreshes Facebook's cache, which is shared with Instagram. The Twitter Card Validator (cards-dev.twitter.com/validator) tests Twitter-specific tags. LinkedIn's Post Inspector and Discord's embed preview (just paste a URL in a private server) round out the testing toolkit.
How this is calculated
Facebook's Sharing Debugger shows exactly what Facebook extracted from your page: title, description, image, URL, and type. It also reports warnings (image too small, missing tags) and lets you force a re-scrape. Twitter's Card Validator requires a logged-in Twitter account and previews how your card will appear in the timeline. The most common issue across all debuggers is the image not appearing, which is usually caused by a missing or incorrect og:image:secure_url (for HTTPS), the image being on a different domain without CORS headers, or the image taking too long to fetch (>5 seconds timeout on most platforms).
Verdict
Test with the Facebook Sharing Debugger first, because fixing FB issues usually fixes every other platform too. Then validate on Twitter. For messaging apps (Discord, Slack, WhatsApp, iMessage), test manually in a private conversation. Add all four debugger URLs to your pre-launch checklist.