I have a .Net app, which works with SFDC via REST API. Not so long time ago we faced with big files. Usually they were around 2-3 Mb and it was OK for both .Net app and SFDC. Now there are some changes in app, which generate those files (file is archive which contains a number of files, the big part of the archive is a png file). As I can see from documentation, neither SOAP API, nor REST API allow me to create an Attachment with size more than 5 Mb. This Attachment is linked to a custom object. Is there any way to upload or create smth to attach file to an object? Maybe through Email attachments. They allow to attach 25 Mb. Maybe upload somehow asynchronously? But how?
With Summer '14 release, file size limits for attachments were increased to 25MB, so you should be fine: