Filestack vs FileUp

Filestack is a file-upload and processing API that handles ingestion from local disk, cloud drives, and URLs, plus on-the-fly transformations like image resizing and document conversion. A live POST against the real gateway, www.filestackapi.com/api/store/S3, returned a 400 without a valid key, reconfirming API-key auth and HTTPS, and a follow-up OPTIONS preflight echoed the request Origin in Access-Control-Allow-Origin, resolving cors from unknown to yes. Filestack starts with a free plan for low-volume use and scales into paid Growth, Pro, and Enterprise tiers as upload and processing volume grows.

FileUp is a self-hosted, open-source temporary file-upload and sharing service built on .NET, offering a public REST API for anonymous uploads with configurable expiry times and view limits. A live OPTIONS preflight with an Origin header against the maintainer's own running instance, upload.sinasnp.com/api/public/upload, returned a 204 with no Access-Control-Allow-Origin header, resolving cors from unknown to no; the public upload endpoint requires no auth (only the separate admin panel uses Basic Auth), and HTTPS was reconfirmed. It's a free, open-source project with no paid tier.