Every prompt you wrote, one search away. Saved in this browser; nothing leaves your machine. / focuses search, Enter copies the first result.
Save library as file writes a copy of this page with your prompts inside it. Keep that file in a folder that syncs (Dropbox, Drive, iCloud, OneDrive) and open it on any machine: the prompts come with it, and anything you add there merges back when you import the file here.
The free version keeps up to 10 prompts in this browser. The paid file has no limit and adds Save library as file, Export and Import.