What is the best client side http library to upload multiple files? If it can handle directories that's a huge bonus. I'm looking for something that is open source or free. I'm looking for something like FTP, but that works over http, through the browser. Uploading multiple files through a normal HTML 4.x form is a bit of a hassle when it comes to uploading more than 5-6 files.
Feel free to share your personal experiences.
I'd recommend something like SWFUpload for that. It's main feature is its support for progress bars, but it also allows for queuing files which is particularly handy (this is actually the second time I've recommended it today).
Another option that I have used before is uploading and then extracting ZIP files. I have used PEAR::Archive_Zip to extract. Requires more knowledge on the user's side, but supports directories and unlimited files (depending on the memory alloted to PHP).
Just to make sure other options are documented (SWFUpload is great) - another good solution is FancyUpload2.
Uploadify is also another great multiple file uploader. It was built off of SWFUpload and they added new features to it.
Some of the features that I have found most helpful are:
The user can upload all the files at once using ctrl + clicking on all of the files
As the files are being downloaded a queue is displayed which shows the files being downloaded including a completeion bar.
As files are completed they are removed from the queue
It also allows you to specify which file types the user is able to download (they can only see the ones you choose)
You could use a Java based solution. I've been using JumpLoader on one of my web pages and haven't had any problems with it. It can also upload directories, which other solutions mentioned here do not support.
Take a look at jquery-html5-upload it doesn't require Flash, and has a sexy jQuery API.