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BUL File Extension: What Is It & How To Open It?

Have you ever stumbled upon a file with the cryptic extension “.BUL” and wondered what it contains? You’re not alone. BUL files are relatively uncommon, and their purpose can be a bit of a mystery. This article will shed light on BUL files, explaining what they are, the programs that use them, and how you can open them on your computer.

What is a BUL File

What is a BUL File?

BUL files belong to the broad category of data files. Due to their limited use, there are two main possibilities for what a BUL file might be:

JSim Bullseye Data Format: This is the most specific use of the BUL extension. JSim is a software program developed by The NSR Physiome Project for simulating and analyzing physiological and biomedical models. BUL files store data associated with these simulations, allowing researchers and scientists to analyze and visualize their findings. JSim is compatible with Windows, Mac, and Linux operating systems.

Generic Data File: In some less common instances, the BUL extension might simply be a generic label for a data file used by a specific program. Without additional context or information about the program that created the file, it can be difficult to pinpoint the exact data type stored within the BUL file.

How to Open a BUL File

Opening a BUL file depends entirely on its origin. Here’s how to tackle the two possibilities mentioned above:

JSim Bullseye Data Format:

If you suspect the BUL file is related to JSim, the best course of action is to try opening it with the JSim software itself. JSim should be able to recognize and interpret the data stored in the BUL file. You can download JSim from the NSR Physiome Project website (

Generic Data File:

Identifying the program that created the BUL file is crucial in this case. Here are some strategies to consider:

File Origin: If you received the BUL file from someone else, try contacting them and inquire about the program used to generate the file.

File Location: The location where you found the BUL file might offer some clues. For example, if it’s within a specific program’s folder, it might be data associated with that program.

File Size and Creation Date: While not definitive, the size and creation date of the BUL file might offer hints about its potential content.

Once you have a potential program in mind, search online to see if it supports opening BUL files. You might find information on the program’s website or user forums.

Additional Tips

Online Converters (Use with Caution): There are websites offering online file conversion services, claiming to convert BUL files to more common formats. However, due to the limited nature of BUL files, these converters might not be reliable or may not produce accurate results. Proceed with caution if you choose to explore this option.

Text Editor (Limited Use): In some rare cases, a BUL file might contain plain text data. You can try opening it with a simple text editor like Notepad (Windows) or TextEdit (Mac). However, this will only display the raw text data and might not be human-readable or provide meaningful information.

BUL files can be a bit of a mystery at first glance. However, by understanding their potential uses and employing some detective work, you can usually determine their purpose and the program needed to open them. If you’re dealing with a JSim-related BUL file, the JSim software itself is the solution. For generic BUL files, identifying the originating program is key. Remember, online converters should be approached with caution, and text editors might only offer limited functionality. By following these tips, you’ll be well on your way to unlocking the secrets hidden within those BUL files.