DOWNLOAD File Documentation


Summary

A .download file is an unfinished download, most often Safari’s in-progress download on macOS, where it is actually a small package rather than a plain file. The browser writes incoming bytes here and renames the file to its real name only when the transfer completes. Its MIME type is application/octet-stream. To get your file, resume or restart the download in the same program; a truncated .download stays corrupt no matter what you rename it to.

Technical details

FeatureValue
Full namePartial / incomplete download file
File extension.download
MIME typeapplication/octet-stream
Format typeIncomplete copy of the target file; no format of its own
Main producerApple Safari (macOS); some download managers
macOS formPackage directory (bundle) that looks like one file in Finder
DeveloperApple (Safari) — no single owner across tools
CategoryWeb / temporary file
Magic numberNone of its own — header matches the file being downloaded
ContainsPartial data plus (Safari) a property-list of URL and byte progress
Resume mechanismHTTP range requests, when the server supports them
Renaming works?Only if the transfer actually reached 100%
Safe to deleteYes, if no download is running (gives up resume)
Typical locationThe Downloads folder
Chrome/Edge equivalent.crdownload
Firefox equivalent.part
Related extensions.crdownload, .part, .partial, .opdownload, .tmp

What is a .download file?

A .download file is a staging copy created while a download is still running. It is the same idea as Chrome and Edge’s .crdownload or Firefox’s .part, under a different name. On macOS the main producer is Apple’s Safari: while a download is in progress it keeps the file in the Downloads folder as name.download and renames it to the real filename only when the transfer finishes. Some download managers and older peer-to-peer tools also use the .download suffix. There is nothing to “open” as a .download; the real question is always how to finish or recover the download.

The suffix serves a purpose beyond housekeeping. By not carrying the file’s real extension, the incomplete file is not treated by the operating system as a runnable program or a valid document, which prevents anyone from accidentally launching a half-written installer. The name changes to the true extension only at the moment the bytes are all present.

Safari’s .download is a macOS package, not a plain file

A detail specific to Safari sets .download apart from its siblings. Safari’s .download is not a plain file but a bundle: a directory that the Finder displays as a single item. Inside it are two things: the partially downloaded data, and a property-list record (Info.plist-style) holding the source URL and how many bytes have arrived so far. That property list is what lets Safari resume after a pause, a crash or a reboot, because it knows exactly where to ask the server to continue from.

You can inspect the contents by right-clicking the item and choosing Show Package Contents, which reveals the raw partial data. The supported way to continue, though, is to resume from Safari’s Downloads list rather than poking inside the package, because the list uses the stored progress to issue an HTTP range request for the missing bytes.

The data portion has no format of its own

Technically the downloaded data inside a .download is just the leading bytes of the real file, with no wrapper, header or encryption added by the browser. A partial MP4 starts with the same bytes an MP4 would; a partial ZIP starts like a ZIP. That is why a .download has no magic number of its own: its header is whatever the target file’s header is. It also explains the one rule that governs everything you can do with the file.

Renaming a .download to the real extension produces a working file only when the download was effectively complete, meaning the on-disk size matches the expected size. Renaming changes the name, not the data, so a half-downloaded archive, installer or document stays corrupt regardless of what you call it. Partially downloaded media is the single partial-success case: because MP4 and MKV can be read progressively, VLC can often play the portion of an incomplete video that did arrive, even though the file is truncated.

Frequently asked questions

How do I resume or finish a .download file?

In Safari, open the Downloads list and click the resume (circular-arrow) button on the item. It works while the item is still listed and the server supports resuming; otherwise download the file again from the source.

Can I just rename .download to the real extension?

Only if the download actually completed. Compare the file’s size with the expected size. Renaming changes nothing about the data, so an incomplete file stays corrupt no matter what you call it.

Can I delete .download files?

Yes, if no download is currently running. Deleting one also discards any chance of resuming that download, so resume first if you still want the file. Old, orphaned .download items are safe to remove.

What are the Chrome and Firefox equivalents?

Chrome and Edge use .crdownload, Firefox uses .part, and old Edge used .partial. All are the same mechanism: staging an unfinished download under a temporary name until the transfer completes.

References