Reshuffle is a framework that lets you connect to services, create integrations between systems, and build workflows using these services and systems.
Reshuffle achieves this by using Connectors as the connection mechanism to a 3rd party service or system. Each system Reshuffle connects to has their own connector. If you want to connect to Salesforce, for example, you would use the Salesforce connector.
Reshuffle ships with an existing ecosystem comprising several connectors you can use to connect to common systems. A list of these Reshuffle-provided connectors can be found in this page, and their code can be found in the various repositories here.
The framework is extendable, meaning you can create connectors to services you use or even your own proprietary systems. The process for building new connectors is described in the manual.