Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for service bridges. In one aspect, a method includes a host operating system performs operations comprising: receiving, using one or more service bridges that execute in the host operating system, a plurality of requests from the one or more virtual machines, wherein each service bridge is associated with a different virtual machine of the one or more virtual machines, and wherein each request is a request to interface with one or more external services; modifying, using a respective service bridge, each request to be processed by the one or more external services; and providing each modified request from the respective service bridge to the one or more external services, where the respective service bridge communicates with the one or more external services over a network.