Files with o extension are mainly related to the object file format used by various programming languages and development environments.

There is one other file type using
the O file extension!

empty icon.o - UFO: Enemy Unknown game data

Detailed description

Software that open o file

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O file extension - Object format

What is o file? How to open o files?

File type specification:

Source code and script file type icon Source code and script file type

File extension o is traditionally used for Object file format. These files contain object code and any other related data typically produced by a compiler or assembler. Can also be referred to as Object code or Object module.

Many different object file formats are used, because originally, each computer type had its own unique format, but the file extension and purpose of these files was always the same.

Formats that use o file extension include a.out, COFF, ELF, PE, Mach-O, SOM, Hunk, MZ, ECOFF, XCOFF, NE and LX. These are found mainly used in Linux and Unix-like environment, gaming consoles and even some mobile phones.

Shared libraries (so files) are created from object files.

Updated: November 22, 2023

The default software associated to open o file:

Microsoft Visual Studio icon

Microsoft Corporation logoMicrosoft Visual Studio  Multiplatform software

Company or developer:
Microsoft Corporation

Microsoft Visual Studio is an integrated development environment (IDE) used to create applications for Microsoft Windows, Windows Mobile, .NET Framework, Silverlight as well as dynamic websites and web applications. Visual Studio is available for Windows and Mac.

Help how to open:

The source code can be viewed and edited in many specialized applications.

How to convert:

There is no way how to convert *.o files to other formats.

List of software applications associated to the .o file extension

Recommended software programs are sorted by OS platform (Windows, macOS, Linux, iOS, Android etc.)
and possible program actions that can be done with the file: like open o file, edit o file, convert o file, view o file, play o file etc. (if exist software for corresponding action in's database).

Click on the tab below to simply browse between the application actions, to quickly get a list of recommended software, which is able to perform the specified software action, such as opening, editing or converting o files.

Software that open o file - Object format

Programs supporting the exension o on the main platforms Windows, Mac, Linux or mobile. Click on the link to get more information about listed programs for open o file action.

Microsoft Windows:

Apple macOS / Mac OS X:

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