In smart spaces, multiple connected objects and sensors act in a coordinated manner through automations that are deployed into the environment. A common approach to empowering users to configure the desired automated behaviours is using trigger-action programming (TAP). However, it can be difficult for users to untangle the behaviour of the created rules. In this paper, we propose a novel solution, ExplainTAP, whose objective is to support users in detecting and understanding possible problems between TAP rules (such as conflicts and unexpected direct or indirect rule activations). It also detects inconsistencies between such automations and users’ goals. After the analysis, the tool proposes possible improvements. For this purpose, the tool can also simulate and analyse the context in which rules could be activated and provide explanations about possible issues to make the behaviour of the smart space more transparent. The paper also reports on a user test of the tool with 18 participants, which provided overall positive feedback and highlighted its usefulness.