The share of renewable generation is increasing all around the globe. This is leading to an increased need for designing new electricity markets that are suited to the new reality. Simulation is widely used to experiment and analyze the potential impacts of new solutions, such as novel electricity market designs. This paper presents the Electricity Market Service (EMS) and the Power Flow Service (PFS). The EMS is capable of simulating several electricity markets, namely EPEX SPOT market, MIBEL's day-ahead and intraday markets, Nord Pool day-ahead market. This service is easily integrated with other modules and relies on JSON inputs to execute the electricity markets, supporting different types of offers, namely block offers, flexible offers, and complex conditions. The results are also presented in JSON, including the general market results, as well the results by player. The PFS is responsible for creating electricity networks and evaluating them, according to the market results from the EMS. This paper presents a detailed description of how both systems work separately and in sync and how the connection to the external system can be accomplished. A case study involving the MIBEL market, using real players and offers data, based on a real power network from Portugal is presented.