What is a merchant ID? Tom Woodward May 29, 2016 14:47 Follow Each MyGate merchant is issued with a MyGate Merchant ID. This identifies the merchant on MyGate's Back Office system. Related articles What is an application ID? Which application ID should I use for 1 Click? Which banks can I integrate into? What are all the URLs for live and test modes? Comments 0 comments Please sign in to leave a comment.