What is a .properties file?
Java Properties File · Code and data · Sun Microsystems · 1996
A .properties file is a simple key-value configuration format from the Java world. Each line is a setting like key=value, widely used for application config and for translations (message bundles).
What is a .properties file used for?
Java properties files are plain text: key=value or key:value per line, with # for comments. They are the standard way Java and Spring applications hold configuration and localised text.
For non-ASCII text, older Java escaped characters as \uXXXX, though modern tools read UTF-8 directly. The files open in any editor.
What opens a .properties file?
The .properties format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- IntelliJ IDEA
- Eclipse
- VS Code
macOS
- IntelliJ IDEA
- Eclipse
- VS Code
Linux
- IntelliJ IDEA
- VS Code
- any text editor
Open a .properties file step by step
- Confirm the file really is a .properties. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
- On Windows, open it with IntelliJ IDEA or Eclipse.
- On Mac, use IntelliJ IDEA or Eclipse.
- On Linux, try IntelliJ IDEA or VS Code.
- Still stuck? Convert the .properties to yaml, which opens more widely.
Why can't I open my .properties file?
Almost always because no installed app understands Properties. Install one of the apps above, or convert the file to a format your existing software already reads. If double-clicking opens the wrong program instead of nothing at all, the file association is set to the wrong app rather than the file being broken.
The other possibility is that the file is not really a .properties at all. Drop it into the file identifier to check it by its bytes instead of its name. Nothing is uploaded.
How to convert a .properties file
You can convert a .properties file to yaml, json using a conversion tool or the export menu of an app that opens it.
Properties has no fixed magic number, so there is no signature table on this page. Its bytes alone do not prove the format: identification relies on the extension, the structure of the content and the program that created it. The magic-numbers reference lists the formats that do carry one.
Frequently asked questions
What is a .properties file?
A .properties file is a simple key-value configuration format from the Java world. Each line is a setting like key=value, widely used for application config and for translations (message bundles).
How do I open a .properties file?
Any text editor opens it, and Java IDEs like IntelliJ IDEA add syntax help. Each line is a simple key=value pair.
What is a .properties file used for?
Configuration and localisation in Java applications: database settings, feature flags and translated message bundles, one key-value pair per line.
How do I handle special characters in a properties file?
Modern tools read UTF-8 directly. Older Java expected non-ASCII characters escaped as \uXXXX, which you can generate with the native2ascii tool.
Related formats
Sources
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