At Clever Cloud, we are working on extremely light virtual machines to run WebAssembly binaries. As it’s WASM, we can write code using a lot of languages. We use a custom unikernel to run this WASM as Function-as-a-Service, using one VM per function execution. These VM can run on events from messages coming through Pulsar, or from HTTP invocation, the run is on-demand as only the consumers stay up. This can be a new model: Pulsar functions for real isolation in multi-tenancy use cases. This talk will show the use case, explain the virtualization underneath and demonstrate the multi-tenancy use case.