e-Invoice API interface is a site-to-site integration of a taxpayer website with the E-invoice system. Large taxpayers can use the API interface to generate bulk INR per day. However, the taxpayer should meet the following criteria to use the API interface: 

• Should automate his invoicing system with IT solutions. 
• He should be ready to change his IT system to integrate with the E-invoice system as per API guidelines. 
• His system should have an SSL based domain name. 
• His system should have a Static IP Address. 
• He should have a pre-production system to test the API interface.