Upstream Oil and Gas Custody Transfer monitoring system in real time using mobile apps. The process of handing over oil and gas products or Custody Transfer is an activity of buying and selling transactions in the form of crude oil, petroproduct, petrochemical and gas by moving from one place to another with one calculation reference point or commonly called the Custody Transfer Measurement System (CTMS) which in the form of flow meters, automatic tank gauging and manual tank gauging. The application was formed by PT Sucofindos HMPM IT team.