Mastodon 2.6.0 introduced simple link ownership verification for links on your profile.
– open the preferences of your profile
– add a link to your website/blog
On your website/blog:
– add '<a rel="me" href="link_to_your_mastodon_account">…</a>' (link to your Mastodon profile)
– the important part is 'rel="me"' in HTML code (part of the backlink)
– link becomes green and a check mark appears
mastodon.at is a microblogging site that federates with most instances on the Fediverse. Note: This instance will shut down on February 29th, 2020.