Invoice4u can automatically register system changes to your own files. By entering you API Call in the following entry box Settings > Online Payments > Settings > API Call
Here is an API call example:
http://www.yourapp.com/api?token=%7B%7Btoken%7D%7D&email=%7B%7Bemail%7D%7D&company_name=%7B%7Bcompany%7D%7D&invoice_id=%7B%7Binvoice_id
The API call can contain essential details regarding transactions, clients and yourself.
{{promocode}}, {{first_name}}, {{last_name}}, {{email}}, {{phone}}, {{post_code}}, {{city}}, {{street}}, {{country}}, {{comment}}, {{quantity}}, {{invoice_name}}, {{invoice_tax_no}}, {{invoice_post_code}}, {{invoice_city}}, {{invoice_street}}, {{invoice_country}}, {{invoice_comment}}, {{generate_invoice}}, {{name}}, {{description}}, {{oid}}, {{paid}}, {{price}}, {{product_id}}, {{id}}, {{referrer}}, {{token}}, {{invoice_id}}