Channel names can contain any unicode character with the following exceptions:

  • They cannot start with a square bracket [
    Square brackets are reserved as a means to provide metadata or instructions to Ably about the intended channel when subscribing.
  • They cannot start with a colon :
    Colons are used to delimit channel namespaces. Find out more about channel namespaces
  • They cannot contain any newline characters (or similar, e.g. carriage return or unicode page separator)
  • They cannot be empty


We do not currently currently enforce a length restriction on the name of a channel. However, the channel name is included in the url for REST requests, and many browsers have issues with URLs over 2048 characters, so we recommend keeping the channel name well under that.