DropChunk live demo

Resumable uploads, without jQuery.

Drop a file below. This page uses an in-memory mock server, so it works by simply opening the file. Break the connection halfway through, then resume and watch only the missing chunks travel.

Try the uploader

Click the dropzone once if you want to paste a file from the clipboard. Images can be resized and compressed in the browser before their chunks are sent.

Pure vanilla JSNo framework and no jQuery dependency.
True resumeThe server is asked what it already has before anything is sent.
Smaller imagesResize and compression happen before upload, not after.
Visual config builderChange settings here and copy the generated init code.

Simulate a connection drop

This is the quickest way to see why resumable chunking matters.

The mock server keeps the chunks it already received. The failing chunk itself is not stored.

  1. Turn the switch on and add a file large enough to produce several chunks.
  2. When the upload stops, click Resume on that file.
  3. Read the log: the status check reports the stored chunks, and only the missing chunks are sent.

Transport log

Status checks, individual chunks, drops, resumes, and completed uploads appear here.