Open Graph Checker (Free)

See why a link preview looks wrong on Facebook, LinkedIn, Slack, Discord or X before you share it: missing or duplicate Open Graph tags, broken or wrong-size images, invalid X card types and og:url/canonical mismatches, for one page, a list of URLs or a whole build folder.

python3 -m ogcheck https://example.com/ https://example.com/blog/post
python3 -m ogcheck --dir dist --base https://example.com/          # before you deploy
python3 -m ogcheck --dir dist --base https://example.com/ --json   # for CI (exit 1 on high-severity problems)

• Open Graph (ogp.me): the four required tags (og:title, og:type, og:image, og:url), og:description, og:image:alt (ogp.me: a page with og:image should have one), duplicates, name= instead of property=, absolute URLs, og:url vs canonical, long titles and descriptions.
• X / Twitter cards: valid twitter:card (summary, summary_large_image, app, player) and X's documented image limits: about 2:1 for large cards, at least 300x157 (144x144 for summary), at most 4096x4096, under 5 MB, JPG/PNG/WebP/GIF, no SVG.
• The image itself: downloaded (or read from your build folder) to confirm it loads, its real format and size, and that og:image:width/height match.
• Across pages: one image reused on most pages, and duplicate titles.

Run ./demo.sh for the example site (5 pages, one per common mistake) and ./run_tests.sh for the tests. Python 3.9+, no dependencies. Live checks block private and local addresses; set OGCHECK_ALLOW_PRIVATE=1 for a local dev server.

Platforms cache previews: after fixing tags, refresh them with each platform's own debugger or post inspector. It reads the HTML your server returns and doesn't run JavaScript, which is also how most preview crawlers work.