O-RAN (Open Radio Access Network) multivendor integration, despite its promise of a diverse 5G ecosystem, faces compatibility challenges such as vendor-specific implementations. We propose WA-RAN, a novel framework that leverages WebAssembly (Wasm) to enhance interoperability and flexibility within the O-RAN architecture. Using Wasm plugins, WA-RAN addresses the complexities of integrating multivendor equipment, enables components update on the fly, and facilitates the introduction of new features. Additionally, it offers platform and language agnosticism along with enhanced security via sandboxing. We demonstrate the design of WA-RAN through two use cases in 5G: a slice scheduler and a near-Real-Time RAN Intelligent Controller (near-RT RIC). Our implementation and evaluation show WA-RAN potential to safely overcome O-RAN integration challenges, providing a promising path to versatile 5G networks.