The .OPDOWNLOAD extension refers to the particular type of incomplete downloads, those that are being downloaded by the Opera browser. Similar to a .part file, the browser augments the .OPDOWNLOAD extension to the ongoing downloads or the files whose download progress has been paused or stopped.

These files can be resumed only from the software that initiated their download. Usually, upon the successful completion of the download, the software will remove the .OPDOWNLOAD extension and add the original file type extension to the completed download.Some popular file types can be accessible through their usual software even though they have a .part file extension associated with them.