Mobile phones and other ubiquitous technologies are generating vast amounts of high-resolution location data. This data has been shown to have a great potential for the public good, e.g. to monitor human migration during crises or to predict the spread of epidemic diseases. Location data is, however, considered one of the most sensitive types of data, and a large body of research has shown the limits of traditional data anonymization methods for big data. Privacy concerns have so far strongly limited the use of location data collected by telcos, especially in developing countries.In this paper, we introduce OPAL (for OPen ALgorithms), an open-source, scalable, and privacy-preserving platform for location data. At its core, OPAL relies on an open algorithm to extract key aggregated statistics from location data for a wide range of potential use cases. We first discuss how we designed the OPAL platform, building a modular and resilient framework for efficient location analytics. We then describe the layered mechanisms we have put in place to protect privacy and discuss the example of a population density algorithm. We finally evaluate the scalability and extensibility of the platform and discuss related work.The code will be open-sourced on GitHub upon publication.