There is a customer registry in Erply.
A customer can be either a company or a person. The main difference is that on Person card, there are fields for "First name" and "Last name", while on Company card, there is just a field for company name (and a drop-down for optionally selecting company type — LLC, PLC etc. However, it is not required and this can be just as well included in the company's name.)
It is possible to associate a person with a company (by filling the “works at” field). At this point, that person becomes a “contact person” and ceases to be a customer in its own right. It is then not possible to create invoices for that person, and it is no longer displayed in the customer list. However, it will be listed as a contact on the parent company card, and when creating an invoice to the parent company, it is possible to pick that person as the contact person for that invoice.
An existing person cannot be converted to a company, or vice versa.
Customers can be grouped into Customer Groups. Customer Groups are hierarchical. Other fields that also allow customer classification to some extent, are:
Assigning a Customer Manager (ie. an employee) to each customer may also be useful if each employee only needs to see their own customers, but not the full list. This restriction can be enabled on User Group card.
Both a customer and a customer group can be associated with price lists — up to 5 price lists for a customer group, up to 3 price lists for a customer. These price lists are applied automatically when selling to that customer.
This is the amount of money that customer owes (expressed as a positive quantity) or the customer’s prepaid amount (expressed as a negative quantity). A customer’s balance is the sum of all invoices made to that customer, minus the sum of all payments made by the customer.
Customer’s balance is displayed at the top of the customer card. There are also a number of related printouts and reports: Balance Report (a list of invoices and payments in chronological order, along with a running total), Balance Statement (more or less the same, meant as a printout for sending to the customer) and Payment Reminder (a list of unpaid invoices, also a printout for sending to the customer).
Balance is not kept for the default anonymous POS customer (and balance can be turned off with a checkbox on customer card, too).
It is possible to set customer’s default payment deadline, which will apply to any invoices made to that customer.