Matrix can be used cross-platform on any client which supports the protocol. offers a built-in WebClient using the Element web client which allows users to login via web browser.

When using a software client the username and password set during the registration process need to be entered as well as the matrix server address

A username is formatted in the syntax or depending on which server the username was initially registered.

The same syntax needs to be used when connecting to other users via a client.

Alternatively to the built-in webclient on the public Element web client can be used as well when selecting as homeserver address.

The following site lists software clients for all possible platforms.