You can use a workflow extension created by a third-party developer to extend the capabilities of Final Cut Pro—work directly with a third-party application inside the Final Cut Pro interface. Workflow extensions include tools for collaboration like Frame.io, stock media like Shutterstock, transcription and captioning like Simon Says, and asset management like CatDV. Learn more about available collections of workflow extensions.
After you install an extension using the manufacturer's instructions, you can access it in Final Cut Pro by clicking the Extensions button 
on the left side of the toolbar. If you installed one extension, only the extension window appears. If you installed multiple extensions, choose the extension you want to use from the menu that appears. Click the Extensions button again to close the window.
For information on how to use an extension, refer to the documentation included with the extension. For technical support, contact the developer of the extension.
