QuickPad

QuickPad is a notepad in your browser side panel that allows for easily adding notes while browsing the web without having to open a separate tab or window. Instead, you can add notes side by side with the web pages or apps you are viewing. The note editor includes basic text editor features, such as text formatting and handling of links. You can also format content using markdown. You can add as many notes as you wish as well as search your notes to easily find one or more specific notes. Your note data is private. All your data is stored in your browser's local database. You can optionally enable automated backups to a folder on your Google Drive.

Screenshots from Chrome Web Store