Save files to user's computer
When I encode an image and try to save it, I can only save it on Replit's computer and not mine.
You can't save file to a user's own computer. As @ch1ck3n said it would be a huge security risk. If website were able to save file to computers, they could potentially install malware. Also, if the code is running on the Replit computers, there is no way of saving it to your own computer as they are completely separate computers. It would be like you running code on your computer to save a file onto my computer.
@CosmicBear ok, but it's possible to implement something similar. For example, a special folder in Replit's computers and any files written there get added to a list on the client, a list of links, and when the user manually clicks the link, the file gets downloaded. And I know that can be done, because many websites do it, just click a link and download whatever file