Resumable upload
Also known as: tus upload, chunked upload, resumable file upload
An upload method that sends a large file in pieces and remembers its progress, so a dropped connection resumes where it stopped instead of starting over.
Updated
What it means
A normal web upload sends a file in one long request. If the connection drops at 90 percent, everything is lost and you start again. A resumable upload breaks the transfer into pieces and lets the server keep track of how many bytes have safely arrived, so an interrupted upload simply carries on from that point.
For video this matters a lot. A day of 4K action footage easily runs to tens of gigabytes, and at a typical home upload speed that is hours of transfer. Over that span, a router restart, a laptop going to sleep or a switch between Wi-Fi networks is almost guaranteed.
How it works in practice
The most widely used open standard is tus, which runs over plain HTTP. The client first creates an upload by telling the server the total file size and gets back a unique URL. It then sends the data in chunks, each tagged with an offset. After an interruption, the client asks the server for the current offset and continues from there. The reference server is tusd, and libraries like tus-js-client and Uppy handle the browser side.
Chunk sizes of a few megabytes to a few dozen are common: small enough that a failure wastes little, large enough to keep throughput high on fast lines. That is why a long chaptered GoPro session can upload reliably even on a shaky connection.
What to watch out for
A browser cannot reopen files on its own after the page is closed. If you reload the tab, most uploaders need you to select the same files again before they can resume, and they match them by name and size, so do not rename or re-export them in between.
Sleep mode is the other killer: many laptops pause network activity when the lid closes, so plug in and adjust power settings for long transfers. Files stored in cloud folders such as iCloud or OneDrive may exist only as placeholders; make sure the raw footage is fully downloaded to the disk before you start. Servers also clear unfinished uploads after a while, so do not leave one paused for days.
How RawClip handles it
RawClip uploads are resumable and run in the background, so a dropped connection does not mean starting again. You can add many MP4, MOV, AVI or MKV files from several cameras in one order, including high Bitrate 4K and 5.3K clips.