A set of modules and functions to support real-time processing of satellite data with pytroll. It requires the Posttroll library for messaging. Satellite data processing is often done in chunks, usually referred to as granules or segments. Several chunks are normally required to cover a given area of interest. When these chunks of data are processed and a Posttroll message is sent modules in Pytroll-collectors support the collection of such chunks into datasets, allowing other (Pytroll) processes to start processing on all the chunks in one batch once all relevant chunks are available. This is, however, only one example of what this package provides. There are also functionality to list and stalk files in an object store like AWS S3 for instance.