Which file types your store actually accepts is up to you — you choose them per Upload Rule in the admin, along with size limits and what happens when a check fails. The categories below are what Filecheck supports, and what it can do with each.
Files are identified by their actual content, not just their file extension. A .pdf that isn’t really a PDF is caught at upload.
PDF
Full preflight checks and automatic fixing.
PDFs can also be validated against official ISO conformance standards: PDF/A-1a, -1b, -2a, -2b, -2u, -3a, -3b, -3u, -4, -4e, -4f (archiving) and PDF/UA-1, -2 (accessibility).
Raster images
Full preflight checks and automatic fixing, using raster-specific checks (resolution, dimensions, color).
Vector
Accepted and converted to PDF, after which the full PDF toolset applies.
Office documents
Accepted and converted to PDF, after which the full PDF toolset applies.
Archives
Accepted and passed through to your order or storage — no checks run on the contents.
Everything else
By default, a Rule rejects file types it doesn’t list. You can instead choose to accept unknown types and hand them off unchecked — useful for reference material or supporting assets.
Size limits
There is no fixed platform limit — you set a maximum size per accepted file type (and an optional total per upload) on each Upload Rule, and uploads are checked against it before processing. Files up to 500 MB are supported. 
