The question is a little abstract so let me explain. Suppose I make a webpage solely for offline use, say an Image Viewer so that users can view their photos full screen. The user has the option to either select files or drag n drop files https://developer.mozilla.org/en-US/docs/Using_files_from_web_applications The files are then iteratively stored in IndexedDB. When the user closes the browser and comes back the next day and opens up the webpage, the images are automatically loaded instead of having the user select the images again. The problem comes when the user first uploads the images. Some images might have the same name. Do I have to check if the 'key' already exists in the DB before hand or can I store the file path of the images in the DB as the key?