There was a GUI to write contracts in Michelson @tezforce

Answer: While there is currently no dedicated GUI for writing contracts in Michelson, there are several plug-ins available for popular text editors such as Visual Studio Code, Atom, and Sublime Text that provide syntax highlighting and autocomplete capabilities to make writing contracts in Michelson easier. Additionally, there are online tools such as TezBridge and Michelson Playground that allow users to write, compile, and deploy contracts in Michelson without the need for a text editor.

There are plug-ins for several text editors.