In some examples, a payment service system receives a request to associate a proxy identifier with a user account of a charity. The proxy identifier is individually distinguishable from other proxy identifiers associated with user accounts of other users, and has a syntax including a symbol and a string of one or more characters. The symbol and the string are concatenated such that the symbol appears immediately before the string. The payment service system receives, via an application on a user device of a user, an input associated with the proxy identifier, and performs a database lookup to identify the user account associated with the proxy identifier. Information associated with the user account of the charity is presented via a user interface presented by the application. The user interface enables the user to donate funds from a financial account of the user to the user account of the charity.