Is there any "mainstream" library used for this purpose? Commonly spread, well maintained, documented etc. I found these (using flash):
- Uploadify - not many releases, latest 12/2010, no documentation (!)
- SWFUpload - latest release 03/2010, documentation
- fancyupload - looks buggy.
- phpfileuploader - looks heavyweight, and looks commercial (?) I cannot read the licence (you can download it but are you allowed to use it forever without paying?)
- plupload
New version of pure javascript (no flash) Valums' ajax upload claims to handle file size limit and progress bar, which is quite suspicious to me: these features require to guess the file size before the upload, which seems impossible in javascript (look also here). Or can it work?