DCU File

What are DCU files and how to open them

Are you having problems opening a DCU 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 DCU files.

What is a DCU file?

DCU files have multiple uses, and Delphi Compiled Unit is one of them. Read more about the other uses further down the page.

Delphi Compiled Unit

.DCU files are compiled source files written in Delphi, a programming language developed by Borland.

A unit file contains the source code of classes and functions, and a corresponding DCU file is produced when the developer compiles the program into executable code.

Delphi is a program used to design other programs. It was originally developed by Borland Software Corporation in 1995 until acquired by Embarcadero Technologies in 2008.

How to open DCU files

We have identified one DCU opener that is compatible with this specific type of DCU file.

Programs that open Delphi Compiled Unit files

Last updated: October 22, 2026

All known file formats using extension .DCU

While Delphi Compiled Unit is a popular type of DCU-file, we know of 2 different uses of the .DCU file extension. Different software may use files with the same extension for different types of data.

Kylix Compiled Unit

A Kylix Compiled Unit file is a binary output produced by the Borland Kylix 3 compiler, storing a module (unit) written in Object Pascal already processed into a form the compiler and linker use. It includes compiled symbol info (types, routines, variables), dependency information, and optionally debugging metadata, based on the source Pascal unit (.pas), in a format suitable for building applications in the Kylix environment.

These files are written by the Kylix compiler during project builds. They are not edited by developers directly - source changes are made in Pascal (.pas) units. The compiler reads these compiled unit files when compiling other modules that refer to them (via the uses clause), so dependencies resolve without recompiling every unit every time.

The internal structure begins with a 32-bit "magic number" that identifies files from various Delphi and Kylix versions. For Kylix 3 compiled units, this magic number is one of values 0x0F1001DD or 0x0F0001DD. Other notable identifiers include a four-byte field at offset 0 matching such magic values. Additionally, bytes at offset 3 have characteristic values that help distinguish between versions.

While we have not verified the apps ourselves yet, our users have suggested two different DCU openers which you will find listed below.

Various apps that use files with this extension

These apps are known to open certain types of DCU files. Remember, different programs may use DCU files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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