1BK File

What are 1BK files and how to open them

Are you having problems opening a 1BK file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your 1BK files.

What is a 1BK file?

A .1BK file is a 010 Editor Bookmark file.

010 Editor Bookmark files are auxiliary data files created by the 010 Editor program (from SweetScape Software) to save bookmarks that a user makes within a document while editing. These bookmarks mark either specific byte positions or ranges in the file, and may include metadata like a name, data type, and display color. They are not the primary edited file but support navigation and analysis within 010 Editor.

When using 010 Editor, bookmarks are created either by toggling a quick bookmark at the caret or selection, or by using the Add/Edit Bookmark dialog to create advanced bookmarks. Advanced bookmarks allow assigning names, interpreting the bookmarked data as built-in or custom-defined types (from binary templates), specifying array size, choosing color, and enabling the bookmark to move with the cursor. Bookmarks are persistent: once created, they are saved so that they reappear when the file is reopened in 010 Editor.

These .1BK files have a fixed internal signature identifying them as 010 Editor Bookmark files. In particular, the file begins with the ASCII signature "%1BK" followed by a fixed sequence of bytes (hex 25 31 42 4B 01 00 00 00) at offset zero.

How to open 1BK files

We have identified one 1BK opener that is compatible with this specific type of 1BK file.

Programs that open 010 Editor Bookmark files

Last updated: August 5, 2026

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about 1BK file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.