1. A method for facilitating text input, comprising: invoking an input assistant from within an application in an operating environment at a client, the input assistant being a standalone input service within the same operating environment as the application and operable to be invoked from within a plurality of applications; receiving a text string from a user in an input field of the application; providing, by the input assistant, input prediction for completing the text string, the providing comprising: selecting an input text of at least a portion of one word in the input field of the application; selecting one or more text assistance services from at least two or more different text assistance services; receiving, by the input assistant, text content related to the input text from the one or more selected text assistance services in communication with the input assistant; and presenting the received text content at the client.