If you use a public visibility setting on a post, it will be visible to everyone, even people who aren’t Fediverse members. This means the post may be indexed by search engines.
You can either make your posts invisible to search engines, or ask search engines not to index your public posts.
Prevent a post being visible to search engines
The surest and safest way to prevent a post ending up on a search engine’s index is to use a non-public visibility setting. Followers-only and Mentioned settings cannot be seen by search engines, so they will not be indexed.
Ask search engines not to index your posts
Mastodon also has an option to request that search engines don’t index your public posts:
- Log in through your server’s website
- Go to Preferences > Other > Opt out of search engine indexing
- Tick the box and click Save changes
However, bear in mind it’s up to a search engine to decide if it wants to honour this request, and less honest search engines may decide to ignore your request. If you want a post to remain off search engines, it’s much safer to use a non-public setting.