Windows
Compatible applications
Quick Facts
Basic information about this file format
Extension
.ARFF
File Type
Attribute-Relation File Format
Category
Data
Best first step
Use compatible software
Quick Summary
A practical overview of the .arff file format
The ARFF (Attribute-Relation File Format) is a text file format developed by the Machine Learning Group at the University of Waikato for describing datasets used in machine learning. It is primarily used with the WEKA (Waikato Environment for Knowledge Analysis) software, but is also supported by o…
File extension
.ARFF
File type
Attribute-Relation File Format
Category
Data
Recommended action
Open with a trusted compatible app
How to open a .arff file
Start with a trusted app that supports this format
- Check the file extension carefully and confirm that the file name really ends with .arff.
- Use software that supports this file type. If one app does not work, try another compatible program for the same platform.
- Update the application if the file was created by a newer version of the software.
- Scan files from unknown sources before opening them, especially documents, archives, scripts, installers, and executable files.
What is a .arff file?
File extension details and usage information
The ARFF (Attribute-Relation File Format) is a text file format developed by the Machine Learning Group at the University of Waikato for describing datasets used in machine learning. It is primarily used with the WEKA (Waikato Environment for Knowledge Analysis) software, but is also supported by other machine learning tools. An ARFF file consists of a header section and a data section. The header section defines the relation name (dataset name) and the attributes (features or columns) of the data. Each attribute is declared with its name and data type (e.g., numeric, nominal, string, date). The data section contains the actual data instances, with each instance represented as a comma-separated list of attribute values. Missing values are typically represented by a question mark (?). ARFF files are designed to be human-readable and easily parsed by machine learning algorithms, making them a popular choice for storing and exchanging datasets in the machine learning community. The format supports various data types and allows for the representation of both numerical and categorical data, making it versatile for a wide range of machine learning tasks.
Software Compatibility
Programs that may open or work with .arff files
macOS
Compatible applications
Linux
Compatible applications
Mobile
Mobile applications
Can .arff files be converted?
Options for saving or exporting this file to another format
In many cases, a .arff file can be converted by opening it in compatible software and using an option such as Save As, Export, or Convert. The available output formats depend on the file type and the application used.
- Use the original software that created the file when possible.
- Check whether the application supports exporting to common formats.
- Be careful with online converters when working with private, business, or sensitive files.
- If conversion fails, the file may be corrupted, incomplete, encrypted, or not actually a .arff file.
Why can't I open a .arff file?
Common reasons this file type may not open correctly
Wrong software
The file may require a specific program that supports the .arff format.
Incorrect extension
The file extension may have been renamed manually, even though the actual file format is different.
Corrupted file
The file may be incomplete, damaged during download, or transferred incorrectly.
Outdated app
Your software may need to be updated before it can open newer versions of this file format.
Frequently Asked Questions
Common questions about .arff files
To open a .arff file, use software that supports this file format.
- WEKA
- RapidMiner
- KNIME
- R (with appropriate packages)
- Python (with appropriate libraries like pandas and scikit-learn)
Open the file in compatible software and look for options such as Save As, Export, or Convert. If no export option is available, the file may require a specialized converter or the original application that created it.
- Verify that the file extension is correct.
- Install or update compatible software.
- Try another application that supports this format.
- Check whether the file is corrupted, incomplete, or encrypted.
A file extension alone does not guarantee whether a file is safe or unsafe. Only open files from trusted sources, scan unknown files before opening them, and be especially careful with executable, script, archive, and document files.
File safety tips
Use caution with unknown files
Only open files from trusted sources. Before opening a .arff file, scan it with antivirus software, verify that the file extension is expected, and avoid running unknown executable, installer, macro-enabled document, or script files.