A Mastodon address has two parts: the local username and the server domain. Two accounts with the same local username on different servers are different accounts unless other public evidence connects them. Compare the full address first, then any public profile details, and do not infer identity from the matching name alone.
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Split the address into two parts
Treat a Mastodon address as a name plus a place, not as a single handle. The part before the @ is the local username chosen on that server; the part after it is the server domain. The documentation describes the address as containing both the local username and the server domain. This means the same readable name can exist in more than one place, and each version is a separate registration. When you are given only a name, you are missing half of the address. [Mastodon Documentation: Username and domain]
- Write the address as name@server and keep both parts together in your notes.
- If someone gives only a name, ask for the server or the public profile address rather than guessing one.
Why two matching names are not one account
The same local username can be registered on different servers, according to the platform documentation. That is the ordinary result of independent servers allowing people to choose names. A match on the left side of the @ therefore tells you that two people picked the same word, not that they are the same person. The right side is what separates them. Comparing only the visible name will merge two unrelated accounts and may attribute one person's public posts to another. [Mastodon Documentation: Username and domain]
- Compare the server domain before comparing anything else.
- Record the full address of each account side by side so the difference stays visible.
A practical comparison method
Start with the full address and check the two parts in order. If the server domains differ, treat the accounts as separate until public evidence shows a connection. If the domains match but the local names differ, they are also separate accounts. Only when both parts match are you looking at the same address. After that, you may look at public profile information that the account holder has chosen to share, but treat each detail as a clue rather than proof. A shared display name, a similar photo, or the same wording in a bio does not establish that two accounts belong to one person.
- Put the two full addresses in a two-column note.
- Mark which part matches and which part differs.
- List public profile details as observations, not conclusions.
| observation | limit | next step |
|---|---|---|
| Local usernames match | The server domains may still differ, so these can be separate accounts | Compare the full address before drawing any conclusion |
| Server domains match | If the local usernames differ, these are different accounts | Check whether the local usernames match exactly |
| Display names or photos look similar | Similarity is not identification and does not prove one person | Keep the full address as the identifying detail |
Stay with public information
Comparing accounts does not require access to private posts or a logged-in view of someone else's settings. Read only what is publicly visible, and stop when the next step would mean accessing a private account or contacting strangers to confirm a guess. Public information can support a cautious observation, but it cannot prove who is behind an account. Avoid covert tracking, attempts to identify a person from a photo, and any message that accuses someone of being a particular person.
- Use only public profile pages or information the account holder has shared with you.
- Do not attempt to access private posts or settings.
- Do not send messages to strangers to test an identity guess.
Separate what you saw from what you decided
A useful comparison keeps three things apart: the observation, its limit, and the practical decision. The observation is the full address and any public profile details. The limit is that a matching name is not identity, a similar photo is not proof, and public information may be incomplete. The decision is what you do next, such as keeping two accounts separate in a contact list or asking someone you already know for the address they use. This structure prevents a small clue from becoming a firm claim.
- Write one sentence for the observation and one for its limit.
- Make the decision only after both sentences are clear.
A hypothetical example
Suppose you are told to look up an account called river on one server, and later you see a different account also called river on another server. The local names match, but the full addresses do not. In this hypothetical case, the correct reading is two separate accounts unless public evidence connects them. You might note that both use the same display name, but you would not write that they are the same person. If you need to refer to one of them, use the full address so the reader knows which server you mean. [Mastodon Documentation: Username and domain]
A couple more questions
Does the same username on two Mastodon servers mean the same person?
No. The same local username can be registered on different servers, so a matching name alone does not show that two accounts belong to one person. Compare the full address and treat other public details as clues, not proof.
What should I do if I only have the username?
Ask for the server domain or the public profile address. Without the server, you have only part of the address and cannot tell which account you mean.
Can I confirm identity by looking at private posts?
No. Private posts are not part of a public comparison, and accessing them is not an appropriate step. Stay with public information and accept that it may not establish identity.
Is a matching photo or bio enough to link two accounts?
No. A similar photo or bio is an observation with limits; it does not prove that one person owns both accounts. Keep the full address as the main identifying detail and look for corroboration only in public information.
Sources & editorial notes
Official references checked on October 23, 2026. Checklists, comparison tables and example wording are DateClues editorial tools, not official tests or validated risk scores.
General information. No guide or tool can certify a person’s identity, intentions or safety. Read our editorial standards.