Members of national parliaments (MPs) often have ties to interest groups, or ‘lobbies’, which might try to influence policies. In order to quantify the influence of lobbies on parliamentary decisions, we design an online platform that allows users to explore votes results, focusing on how interest groups members voted, in order to identify which lobbies voted for or against a given measure and in which proportion. We apply this approach to the specific case of the Swiss Federal Parliament. To achieve this, we build a database that combines two sources of openly available data: (1) a register of politicians’ interest ties, maintained by Lobbywatch.ch , an association dedicated to the monitoring of Swiss politicians’ interest ties and (2) the individual votes results in the Swiss Federal Parliament, accessible through a web-service provided by the parliamentary service of the Swiss government. Our platform allows users to explore the following perspectives of the data: (1) general information about lobbies (e.g. size, domains), (2) individual votes results, with a drill-down by lobby that shows the distribution of votes in each interest group for each specific vote, and (3) overall (dis)agreement of individual MPs with their party and lobbies across all considered votes. We believe that such an exploration platform can be a powerful tool to help quantify the influence of lobbies in politics. Indeed, a qualitative evaluation of the prototype was conducted with 7 domain experts (5 journalists and 2 politicians). They were all able to complete successfully the submitted tasks. They rated its usability and usefulness as rather high (mean respectively 7.4/10 and 6.8/10). Moreover, most of them reported that such a platform has the potential to increase the accountability of politicians towards the people and consequentially to raise the trust of the population in their elected representatives.