  Runtime monitoring is an essential part of guaranteeing the safety of
cyber-physical systems. Recently, runtime monitoring frameworks based on formal
specification languages gained momentum. These languages provide valuable
abstractions for specifying the behavior of a system. Yet, writing
specifications remains challenging as, among other things, the specifier has to
keep track of the timing behavior of streams. This paper presents the RTLola
Playground, a browser-based development environment for the stream-based
runtime monitoring framework RTLola. It features new methods to explore the
static analysis results of RTLola, leveraging the advantages of such a formal
language to support the developer in writing and understanding specifications.
Specifications are executed locally in the browser, plotting the resulting
stream values, allowing for intuitive testing. Step-wise execution based on
user-provided system traces enables the debugging of identified errors.
