Opening UI Files

The UI file type is primarily associated with Qt.

UI	File extension: UI
	File type:	user interface

What is a UI file

UI files mostly belong to Qt by Qt. A UI file contains a form, widget, or user interface created with Qt graphical user interface software development kit. It contains XML-encoded data which defines elements such as toolbars, widgets, functions, tabs, macros, and variables. Qt compiles code stored in a UI file to C++ code at compile time. Its QUiLoader class dynamically constructs user interfaces from UI files at runtime.

How do you open UI files?

You need a suitable software like Qt to open a UI file. Without proper software you will receive a Windows message "How do you want to open this file?" or "Windows cannot open this file" or a similar Mac/iPhone/Android alert. If you cannot open your UI file correctly, try to right-click or long-press the file. Then click "Open with" and choose an application. You can also display a UI file directly in the browser:. Just drag the file onto this browser window and drop it.

Online UI Text Viewer

Choose your .ui file to analyze

or drag and drop it here

Online File Viewer

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UI file format:

If you can determine the file format, the associated program can also be determined. Often, the file format can be deduced from the file extension or the initial bytes (called the signature). If the file extension or signature does not match the file format, errors will occur when opening or editing the file. When there is a problem with a file, the first step to solving it is to determine the file format. Below is our analysis of the UI files:

The UI file extension is used very often and mainly uses a defined UI format. But the following two file formats are common:

• 70% of all UI files are Qt User Interface files, which are based on the XML file format. The Extensible Markup Language (XML) is a simple text-based format for representing structured information: documents, webpages, data, configuration, books, transactions, invoices, and much more. XML defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. The contents of these files can even be read by a human. UI files can be up to 330 KB in size, but are often around 2 KB - 48 KB. The file type is relatively new. Certain words are almost always found in the files, such as <?xml version="1.0" encoding="UTF-8"?>, <ui version="4.0">, <property name="geometry">, <rect>, <x>0</x>, <y>0</y>, <class>MainWindow</class> and <widget class="QMainWindow" name="MainWindow">. An example of a file name is MainWindow.ui. Files like these are about window, dialog, login, form, guimain, screen and widget.
• 9% of all UI files start with the magic bytes Eternity Engine UI File 0.3, which are always the first bytes of this file format. They consist of illegible, cryptic characters. UI files are between 2 KB and 37 KB in size. The following keywords are characteristic: Eternity Engine UI File 0.3. mainbar_new.ui is a typical file name. These files are often associated with mainbar.

All the rest of the UI files (21%) have different formats, often, for example, UGC. Files like these are sometimes linked to customization, creo, parametric, longer or lerdge. Just click the "Choose your .ui file to analyze" button on this page to find out what your UI file is.