The WeChat merchant number is a unique merchant number obtained after the merchant applies for and submits WeChat payment.

The API key is found and set in payment management, api management, and key management. This is equivalent to the merchant's payment key.

The WeChat merchant account is also called WeChat merchant ID. It is composed of pure numbers. As long as the certified service account is applied for and obtained by WeChat payment, the merchant will have this ID number. It is a WeChat public account merchant applying for WeChat payment. Afterwards, the merchant’s payment account is assigned by WeChat Pay. Its parameter name: mch_id.

The API key is the key used to generate signatures during the transaction process. It is only retained in the merchant system and WeChat payment background and will not be spread on the network. The merchant must keep the key properly and do not transmit it on the network or store it in other clients to ensure that the key will not be leaked. Merchants can log in to the WeChat merchant platform according to the email prompts to set up. You can also click the path setting: WeChat Merchant Platform (pay.weixin.qq.com)-->Account Settings-->API Security-->Key Settings.