GMSL’s operations clients include:
| BG International | Deutsche Bank | Fortis | Morgan Stanley |
| BHP Billiton | Distrigas | Gaselys | Nexen |
| BNP Paribas | EGL | Gazprom M&T | Petgas |
| British Energy | Electrabel | GdF Suez E&P | RBS Sempra |
| Business Energy | Eneco Energie | Glencore | Sonatrach |
| Cargill International | Enel | Hepgco | Statoil Hydro |
| Citigroup | Energy Logistics | Hess Limited | Total G&P |
| Chevron | ENOI | Marathon Oil | Vattenfall |
| ConocoPhillips | E.ON Ruhrgas | Macquarie Bank | Vitol |
| Delta | ESBI | Mercuria Energy | ZMB |
GMSL's Software Clients Include:
| Atel Trading | Edison | Glencore | RWE Trading |
| Barclays Capital | EGL | Hepgco | Scottish & Southern |
| BG International | Electrabel | Intergen | Scottish Power |
| Bord Gais | Energie Logistics | JP Morgan | Shell |
| BP | ENI UK | Louis Dreyfus | Soteg |
| Cargill International | ENI SpA | Macquarie Bank | SPE |
| Centrica | ENOI | Maersk | StatoilHydro |
| Chevron North Sea | E.ON Energy Trading SE | Morgan Stanley | TAQA |
| ConocoPhillips | EOS | Nexen | TFE Norge |
| Delta | Gas Natural | Norsk Hydro | Total G&P |
| Direct Energie | Gaselys | Nuon | UBS |
| Dong | Gazprom M&T | RBS Sempra | Vitol |
| EDFT | GE Plastics | RWE Midstream | ZMB |
