A Multi-Level Approach to KPI Definition, Configuration and Computation for Executable Domain-Specific Languages In this project, we assist domain experts and end users in evaluating the performance of their systems during the design phase, before a real implementation. Therefore, we propose a multi-level MultiLevel4KPI approach that enables performance assessment across heterogeneous xDSLs and their systems without modifying the original languages. The approach involves three roles operating at specific levels: a Language Engineer, a Domain Expert, and an End User. At the top level, the language engineer designs the xDSL itself, while the domain expert and end user collaborate on performance evaluation at their own abstraction level. The approach is mainly based on the Generic Performance Evaluation Language (GPEL), a generic performance language that relies on a Trace Domain Query Language (TraceDQL) to help extract data from the execution traces of simulated models for Key Performance Indicator (KPI) computation.