Revit API Integration Services are widely used by AEC professionals and software developers to automate tasks, create custom tools, and connect Revit with other platforms or systems. These integrations help enhance project efficiency, data management, and collaboration. When it comes to software and tools used for Revit API integration, here are some of the most commonly used ones:

1. Autodesk Revit API (C# and .NET Framework)
The core of Revit API development relies on Microsoft’s .NET Framework, especially using C# as the programming language. Developers typically use Visual Studio to write, debug, and compile their Revit add-ins. The Revit API allows access to almost every element within Revit, such as geometry, families, parameters, schedules, and more.

2. Visual Studio
Microsoft Visual Studio is the primary IDE (Integrated Development Environment) for Revit API projects. It supports NET-based development and offers powerful debugging and coding features, making it ideal for creating Revit add-ins, plug-ins, and automation tools.

3. Dynamo for Revit
While not a traditional coding platform, Dynamo is a visual programming tool integrated with Revit. It allows users to create scripts and automate tasks without deep coding knowledge. It's often used in early-stage Revit automation and for rapid prototyping.

4. RevitPythonShell / pyRevit
These tools enable scripting inside Revit using Python, offering an alternative to C#. RevitPythonShell and pyRevit are popular among those who prefer Python for automating workflows and customising Revit environments.

5. BIM 360 / Autodesk Construction Cloud APIs
For cloud-based Revit integrations, particularly those related to model collaboration and data exchange, APIs from BIM 360 or Autodesk Construction Cloud are commonly utilised. These allow developers to integrate Revit workflows with other project management tools and databases.

Revit API Integration Services rely heavily on C#, .NET, Visual Studio, Dynamo, and Python-based tools like pyRevit. Depending on your project's scope, these tools can be combined to automate modeling tasks, create custom UI elements, or connect Revit with other applications or cloud platforms.