BJL File

What are BJL files and how to open them

Are you having problems opening a BJL 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 BJL files.

What is a BJL file?

A .BJL file is a B4J Layout file.

B4J Layout files are layout definitions used by the B4J visual designing tool from the B4X suite of development tools. They define the structure, appearance, and behavior of graphical user interface forms for desktop or JavaFX applications. The internal designer in B4J writes these files when a layout is saved using the GUI designer. Panels, controls, variant layout data for different sizes, anchors, events, visual properties such as colors, borders, fonts, visibility settings, and parent-child relationships among UI elements are encoded in the layout.

The format is binary rather than plain text. A tool called BalConverter (and other community tools) can convert these layout files to a structured JSON form, or back from JSON, facilitating version control, editing outside the IDE, or sharing in text format. The layout definitions include containers ("MainForm"), controls, layout variants, event names, custom views, and font specifications among other attributes.

Signature details include a known binary header at the very start: bytes 0x05 00 00 00 at offset 0, followed by other fixed byte sequences, and the presence of strings like "DBASIC.DESIGNER.DRAWABLE.COLORDRAWABLE", "HANDLERESIZEEVENT", "MAINFORM", "VARIANT0", among others that serve as internal identifiers.

How to open BJL files

Important: Different programs may use files with the BJL file extension for different purposes, so unless you are sure which format your BJL file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: August 24, 2026

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