Client scripting permits end users to customize content, layout or style of their favourite websites. But current scripting suffers from a tight coupling with the website. If the page changes, all the scripting can fall apart. The problem is that websites are reckoned to evolve frequently, and this can jeopardize all the scripting efforts. To avoid this situation, this work enriches websites with a "modding interface" in an attempt to decouple layman's script from website upgrades. From the website viewpoint, this interface ensures safe scripting, i.e. scripts that do not break the page. From a scripter perspective, this interface limits tuning but increases change resilience. The approach tries to find a balance between openness (scripter free inspection) and modularity (scripter isolation from website design decisions) that permits scripting to scale up as a mature software practice. The approach is realized for Greasemonkey scripts.