I am approaching the limits of my hosting plan. I doubled it once from 2 to 4 GB and my site (a popular woodworking community in Hebrew) is getting close to using the disk space available for the images people are uploading.
I was wondering if it were a legitimate use of DropBox (or any of the other free cloud hosts), to serve the files of it as public files... i.e. whenever someone uploads a file to my server it will be instead uploaded using the DropBox API to the DropBox servers, and the Public LINK to the file will be stored in my DB and served to the users.
Another option would be to upload to a hosting server in GoDaddy (I can afford those prices), but that would require writing my own client, which isn't ideal (a good exercise, but I don't have the time).
Obviously the site also generates a fair amount of traffic, I would not ask if it were for personal/close friends usage, I'm talking about many thousands of hits per day...
Update: an answer and comment mention that "Dropbox public links have a bandwidth limit. 20 GB/day for Free and 200 GB/day for Pro." https://www.dropbox.com/help/45 - this seems to suggest that as long as my bandwidth requirements are somewhere below this number, then I am in the clear... Is that so?
Dropbox has bandwidth limits. I use it quite often for running simple static websites for internal testing, but it there are limitations.
Take a look at this: https://www.dropbox.com/help/45
Look in to Rackspace Cloud Files and Amazon S3. You can hotlink directly to the files.
Alteratively, have your users use an image hosting service like Flickr or photobucket, and have them provide links instead.
As far as I know, Dropbox "Free" is only for private usage. They also have business plans. I would consider to upgrade your existing host for a few more dollars.
Whether it's legitimate or not, Dropbox will no longer allow it as of 2017. From https://www.dropbox.com/help/16:
The Public folder
Important changes to the Dropbox public folder
Dropbox accounts created after October 4, 2012 won't have a Public folder. If you'd like to quickly share files you can use a shared link. Shared links work even if the person you're sharing with doesn't have a Dropbox account.
Dropbox Basic (free) users
> As of March 15, 2017 the Public folder in your Dropbox account has been converted into a standard folder. By default this folder is private to your account. This transition will occur automatically.
Here's what you need to know:
All of the files in your Public folder will remain safe, but public links to those files will stop working If someone visits a link to a file in your Public folder, they'll see an error page To see a list of your public links, visit the Public folder—any file in this folder will have previously had a public link associated with it Dropbox can't convert existing public links into Dropbox shared links If you'd like to re-share any of the files in your Public folder, please use a shared folder or shared link Using the public folder to render HTML content
As of October 3, 2016 Dropbox Basic (free) users can no longer use public links to render HTML content in a web browser. If you're a Basic user, and you created a website that directly displays HTML content from your Dropbox account, it will no longer render in the browser. The HTML content itself remains safe in Dropbox, and you can share it using any of our other sharing methods.
> Effective September 1, 2017, Dropbox Pro and Business users will no longer be able to render HTML content, and the Public folder and its sharing functionality will be disabled. Until that date, Dropbox Pro and Business users can continue to use public links to render HTML content.
来源：https://stackoverflow.com/questions/10838988/is-it-legitimate-to-use-dropbox-as-file-storage-for-my-site