I have been testing Shopify's support for uploading files, to see how it compares to other hosted platforms.
For files that are not supported natively by Shopify (such as software files like max, indd, midi or educational tutorial files) there should be ability to download such files for users who can use the files. Having found no list of supported/unsupported files that can be uploaded by Shopify, I have been suprised with some simple tests that Shopify actually modifies files that are uploaded.
So I tried some widely supported files to keep things simple, such as animated svg and animated png files as most browsers support these, but low and behold this first test proved to be a problem. I tried to use Shopify Theme Kit to see if it would sync files reliably instead of uploading in the browser, but no, the files are still modified by Shopify. Shopify clearly is not capable of faithfully uploading files it uploads.
Is there a list detailing the limitations of Shopify files? As going forward Shopify file upload support is proving to be a concern.
@StevenPM I can't speak to Shopify's limitations, but the Customer Fields app offers nice support for file uploads, although it's primarily used for customer registration forms. See developer documentation for support with building custom forms with file uploads.