CLAS file format description

Many people share .clas files without attaching instructions on how to use it. Yet it isn’t evident for everyone which program a .clas file can be edited, converted or printed with. On this page, we try to provide assistance for handling .clas files.

1 filename extension(s) found in our database.

.class - Java Class Data

The CLASS application files are related to Java Runtime Environment. The CLASS file is a Java Class Data. CLASS file contains bytecodes for the Java Virtual Machine. Java is a class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible.

Java Runtime Environment
Application files
- / -
cla, clas, cls
Java Class Data related extensions:
Windows Command File
QlikView Sense App
SmartStart Array Configuration Script
U3 Package
Visual Basic Module
Windows Command File

Naturally, other applications may also use the .clas file extension. Even harmful programs can create .clas files. Be especially cautious with .clas files coming from an unknown source!

Can't open a .clas 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 can't open this file:


To open this file, Windows needs to know what program you want to use to open it. Windows can go online to look it up automatically, or you can manually select one from a list of programs that are installed on your computer.

To avoid this error, you need to set the file association correctly.

The .clas file extension is often given incorrectly!

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

cals, cas, cla, cls, las

Is it possible that the filename extension is misspelled?

Similar file extensions in our database:

CALS Compressed Bitmap
CLASS Group Abbreviation
Java Class Data
Comma-Delimited ASCII Text
Visual Basic Class Module
ArcInfo Geocoding Classification Data

Operating systems currently supports the following operating systems:

Windows XP/Vista, Windows 7/8/10, Windows 11, CentOS, Debian GNU/Linux, Ubuntu Linux, FreeBSD, macOS, Mac OS X, iOS, Android

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If you have useful information about the .clas file format, then write to us! >> CLAS file