How Tumblr caches link posts
Tumblr fetches OG data once when a link post is created and bakes the preview card into the post content. There is no cache TTL – the preview data lives as long as the post does.
No public debugger
Tumblr has no preview or debugging tool for link posts. You can’t see what Tumblr will extract before posting.
Forcing a cache refresh
The only way to update a link post’s preview:
- Delete the post
- Create a new link post with the same URL
- Tumblr re-crawls and builds a fresh preview card
There is no mechanism to refresh an existing published post’s preview.
Reblog chains
This is the Tumblr-specific pain point. When a link post is reblogged, the reblog carries the original preview data. Reblogs are copies, not references – updating the source post (or even deleting and recreating it) has no effect on existing reblogs. If a link post with bad OG data spreads through reblog chains, those reblogs are permanently frozen with the old preview.
When caching goes wrong
- Old preview on your post – delete and recreate
- Reblogs showing old data – reblog chains are immutable, nothing you can do
- Preview missing after recreation – your server likely returned an error during the re-crawl