Workflow Server is a ready-to-use Workflow Engine-based application that you can deploy into your infrastructure. It can be integrated with NodeJS, PHP, Ruby, .NET, or Java applications via a REST API. Workflow Server is a key component for managing the lifecycle of business objects within your enterprise. (by optimajet)
Appwrite - The Open Source Firebase alternative introduces iOS support . Appwrite is an open source backend server that helps you build native iOS applications much faster with realtime APIs for authentication, databases, files storage, cloud functions and much more!