CoreUpload vs the alternatives
An honest look at how CoreUpload compares with the popular JavaScript uploaders. All of the libraries below are good at what they do — the right choice depends on your stack and how much of the server side you want to build yourself.
Uppy, Dropzone.js, FilePond and FineUploader are client-side libraries: they hand you a great browser UI, and you build (or buy) the receiving endpoint, the chunk assembler, the resume store, and the cloud signing service.
CoreUpload is a client + server component for ASP.NET Core. The same package ships the browser runtime and the endpoints that receive, validate, assemble, resume and store the bytes — wired up with app.MapCoreUploadEndpoints() and a <core-upload> Tag Helper.
If you are not on .NET, one of the libraries below is likely the better fit. If you are, the comparison is mostly about how much plumbing you want to own.
Pick a comparison
The closest feature match: tus, S3 multipart, remote sources and resumable uploads. Differences are mostly about the server half.
The framework already receives files. This is about the browser half it does not provide - progress, chunking, resume and validation before the transfer.
Dropzone is the classic lightweight drag-and-drop uploader. Compare scope, chunking and what you still have to write.
FilePond has a polished UI and a rich plugin ecosystem (including Pintura for image editing). Compare image handling and integration.
A long-standing uploader with chunking and S3 support. Compare maintenance status, transports and resume behaviour.
What CoreUpload brings to the table
Every capability below is implemented in the shipping component — each one has a live demo you can try.
| Capability | What it means | Demo |
|---|---|---|
| 7 transport strategies | Single POST, server chunked, direct-to-S3 multipart, direct-to-Azure Blob, direct-to-GCS resumable, tus 1.0, and server-side URL import. | S3, tus |
| Cross-session resume | Queue and file blobs persist in IndexedDB, so an interrupted upload survives a reload and continues where it stopped. | Resume |
| Cross-tab coordination | The same file opened in two tabs is uploaded once, not twice, with an aggregated multi-tab view. | Cross-tab |
| Adaptive concurrency | AIMD concurrency control, a circuit breaker for failing endpoints, and an optional bandwidth cap. | Concurrency |
| Encryption at rest | AES-GCM-256 encryption in the browser before a byte leaves the machine. | Encryption |
| Image pipeline | Content-aware crop, annotate/redact, watermark, EXIF auto-orient, HEIC decode, AVIF/WebP output. | Editor |
| Capture sources | Webcam, screen and audio capture as first-class upload sources. | Webcam |
| Validation & safety | Magic-byte MIME sniffing (not just extensions), plus virusScan and content-moderation hooks. | MIME |
| Localization | Built-in locale packs including right-to-left languages. | i18n |
When another library is the better choice
- You are not on .NET. CoreUpload's server half targets ASP.NET Core. For Node, PHP, Rails or Django, a client-only library plus your own endpoint is the natural fit — our sibling MultipleUpload is the backend-agnostic option.
- You only need a drop zone. If a simple POST of a few small files is the whole requirement, a smaller library carries less weight.
- You need a hosted pipeline. Services like Uploadcare, Filestack, Cloudinary and ImageKit bundle CDN delivery and on-the-fly transformations. CoreUpload uploads into your storage and leaves delivery to you.