Saved web page created by Opera Mini, a web browser for mobile platforms; saved in the Opera Binary Markup Language (OBML) format, which can only be opened with the Opera Mini browser.

The OBML15 file format is designed to reduce the size of downloaded web content, which is helpful for users that want to save and revisit web pages without an Internet connection. It is also useful if you are dealing with low power or memory on your device or downloading content on a slow network. The OBML15 file replaced the .OBML extension with the release of version 5 of the Opera Mini web browser. It was then replaced by the .OBML16 extension with the release of version 7 of the Opera Mini web browser. NOTE: The OBML15 file is not supported by Opera Mini web browser 7 or later.