We recommend using the Flex Message Simulator to create a Flex Message prototype. For more information, see the news from January 18, 2022, Development of the LINE Bot Designer has been terminated.
LINE Bot Designer

About
What is LINE Bot Designer?

Bot Designer supports all types of LINE message templates
Create various types of LINE messages through LINE Bot Designer and implement any chatbot scenario you desire. Messages created through LINE Bot Designer generate JSON code which can be later used for actual chatbot development.
LINE Bot Designer allows you to have the real chatbot experience
You can test the various chatbot service environments available in a LINE chatting room. LINE Bot Designer provides rich menu and web app configuration, along with an emulator supporting various resolutions.
Create various service scenarios using LINE Bot Designer!
LINE Bot Designer was built for designers who want to launch a business using chatbot or to plan a new chatbot service or to design awesome chatbot messages.
LINE Bot Designer is available for free
LINE Bot Designer is free for use.You will need to log in with your LINE account when launching LINE Bot Designer.
Recommended operating systems: Windows 10 and macOS (Sierra or above).
Create any type of chatbot you want with LINE Bot Designer.