Safe, shared-memory interoperability between languages with different type systems and memory-safety guarantees is an intricate problem as crossing language boundaries may result in memory-safety violations. In this talk, I’ll present RichWasm, a higher-level version of WebAssembly with an enriched capability-based type system to support fine-grained type-safe shared-memory interoperability. RichWasm is rich enough to serve as a typed compilation target for both typed garbage-collected languages and languages with an ownership-based type system and manually managed memory. RichWasm takes inspiration from earlier work on languages with linear capability types to support safe strong updates, and adds analogous unrestricted capability types for garbage-collected locations, allowing a module to provide fine-grained memory access to another module, regardless of memory-management strategy. RichWasm types are not intended to be made part of core Wasm; instead we compile RichWasm to core Wasm, allowing for use in existing environments. We have formalized RichWasm in Coq and proved type safety via progress and preservation.