Which API would you use for notifications that match a specific SOQL query?

The Streaming API is specifically designed for use cases where real-time notifications about changes to Salesforce data are required. It allows developers to subscribe to a channel and receive notifications based on specific SOQL queries. This means that when data that matches the criteria defined in your SOQL query is created, updated, or deleted, the Streaming API will push notifications to subscribed clients.

This capability makes the Streaming API particularly useful for applications that need timely updates without the overhead of constantly polling the server, as it operates on a publish-subscribe model. By using the Streaming API, developers can efficiently manage real-time data changes, making it a suitable choice for integrating applications that require immediate awareness of data changes in Salesforce.

Other APIs, while they may serve other purposes, are not designed specifically for real-time notifications based on SOQL queries. For instance, the BULK API is aimed at large-scale data uploads or downloads, the SOAP API is primarily for leveraging standard web service functions, and the REST API is more about traditional RESTful communication rather than event-driven notifications. Thus, for the requirement of notifications that match a specific SOQL query, the Streaming API is the most appropriate choice.