Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for indexing actions for resources. In an aspect, a method receiving, for each resource a plurality of resources that are each accessible by a user device, action data describing actions supported by each resource, each action being an action that can be performed by the user device processing the resource; for each resource: determining, from the action data, an action type for each action supported by the resource, determining, from the action data, action parameters for each action supported by the resource, and indexing the action data, action types and action parameters for the resource in an index that is searchable by a search engine.