A popular form of software reuse involves linking open source software (OSS) libraries hosted on centralized code repositories, such as Maven or PyPI. The size of such repositories keeps increasing at an astonishing speed, and the network of dependencies among the libraries they host is only a very crude way to reflect the real impact of those dependencies, especially for what concerns bugs and vulnerabilities. It is becoming more and more urgent to develop techniques that aim at analyzing dependencies at a finer level (i.e., at call level). This is precisely the goal of the EU project FASTEN. The purpose is to be able to perform a more sophisticated analysis of security-vulnerability propagation, licensing compliance, and dependency risk profiles (among others) by relying on the call-level dependency network of the whole software ecosystem.