Web syndication formats

Atom Syndication Format (XML)-used for web feeds Atom Publishing Protocol (HTTP)-protocol for creating and updating web resources

OPML (Outline Processor Markup Language) is an XML format for outlines (defined as "a tree, where each node contains a set of named attributes with string values"). Originally developed by UserLand Software as a native file format for the outliner application in its Radio UserLand product, it has since been adopted for other uses, the most common being to exchange lists of web feeds between web feed aggregators.

SyncML, or Synchronization Markup Language, was originally developed as a platform-independent standard for information synchronization. Established by the SyncML Initiative, this project has evolved to become a key component in data synchronization and device management. The project is currently referred to as Open Mobile Alliance Data Synchronization and Device Management. The purpose of SyncML is to offer an open standard as a replacement for existing data synchronization solutions; which have mostly been somewhat vendor, application, or operating system specific. SyncML 1.0 specification w

formats for the sharing of search results suitable for syndication and aggregation

GTFS, or the General Transit Feed Specification, is a general transit feed specification which defines a common data format for public transportation schedules and associated geographic information. GTFS contains only static or scheduled information about public transport services, and is sometimes known as GTFS Static or GTFS Schedule to distinguish it from the GTFS Realtime extension, which defines how information on the realtime status of services can be shared.

WebSub (formerly PubSubHubbub) is an open protocol for distributed publish–subscribe communication on the Internet. Initially designed to extend the Atom (and RSS) protocols for data feeds, the protocol can be applied to any data type (e.g. HTML, text, pictures, audio, video) as long as it is accessible via HTTP. Its main purpose is to provide real-time notifications of changes, which improves upon the typical situation where a client periodically polls the feed server at some arbitrary interval. In this way, WebSub provides pushed HTTP notifications without requiring clients to spend resource

open protocol which allows the creation and consumption of queryable and interoperable RESTful APIs in a simple and standard way

Google Data Protocol