A daily updated filename extension database!

DEFS file extension

The table below provides useful information about the .defs file extension. It answers questions such as:

  • What is the .defs file?
  • What program do I need to open a .defs file?
  • How can the .defs file be opened, edited or printed?
  • How can I convert .defs files to another format?

Table of Contents

We hope you find this page helpful and a valuable resource!

1 extension(s) and 0 alias(es) found in database

✅ BlueJ Settings File

DEFS file is a BlueJ Settings File. BlueJ is an integrated development environment (IDE) for the Java programming language, developed mainly for educational purposes, but also suitable for small-scale software development.
Application: BlueJ
Mime-type: application/octet-stream
Magic number: -
Magic string: -
Sample: -
DEFS aliases:
DEFS related links:
DEFS related extensions:
Java Archive

Java Source Code

BlueJ Context File

BlueJ Package

BlueJ Template File

Other types of files may also use the .defs file extension.

🚫 The .defs file extension is often given incorrectly!

According to the searches on our site, these misspellings were the most common in the past year:

def, des, dfs, efs, refs

Is it possible that the filename extension is misspelled?

We found the following similar file extensions in our database:

C++ Definition File
Resilient File System Image
BrainSuite Surface
Binary Editor Definition Data
OpenVSP v2 VSP Design Document
SmartWare Sort Definition File
SmartWare Definition Data
Dragona Online Game Data
Doom 3 Map Definition Data
SQ-80 Sample

🔴 Can't open a .defs file?

When you double-click a file to open it, Windows examines the filename extension. If Windows recognizes the filename extension, it opens the file in the program that is associated with that filename extension. When Windows does not recognize a filename extension, you receive the following message:

Windows cannot open this file:


To open this file, Windows needs to know what program you want to use to open it...

If you don't know how to set the .defs file association, check the FAQ.

🔴 Can I change the extension of files?

Changing the filename extension of a file is not a good idea. When you change a file's extension, you change the way programs on your computer read the file. The problem is, changing the file extension does not change the file format.

If you have helpful information about the .defs file extension, write to us!

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