Your Public Account ID can be found under the Settings > Account page of your account. It starts with "AA", uses UPPER-CASE letters and numbers, and is 16 characters long in total.
Public Account ID vs Username
The purpose of the public account ID is so that you can keep your login username private.
|Public Account ID||Username|
|Created by Kraken (automatically) after signup||Created by you during signup|
|Used for discussing your account with 3rd parties
(including Kraken Support)
|Used only for login|
|Cannot be changed||Cannot be changed|
Never share your username with anyone.
When discussing your account (even if its with Kraken Support), only use the Public Account ID. If someone asks for your username, it's most likely a phishing scam.