Holehe License: Understanding the GPL-3.0 Terms for the Email Checking Tool

The holehe project by megadose is released under the GNU General Public License v3 (GPL-3.0), requiring that any distributed derivative works maintain the same copyleft licensing terms.

The holehe repository is an open-source email checking tool that allows users to verify if an email address is registered across various online services. Before integrating this tool into your workflow or distributing modified versions, understanding the holehe license terms is essential for compliance. According to the megadose/holehe source code, the project explicitly declares GPL-3.0 as its governing license in both the repository documentation and package metadata.

Locating the License Files in the Repository

The primary license documentation resides in the LICENSE.md file at the repository root. This file contains the complete text of the "GNU GENERAL PUBLIC LICENSE Version 3, 29 June 2007" as specified in the source【/cache/repos/github.com/megadose/holehe/master/LICENSE.md】.

Additionally, the setup.py file in the project root declares the license metadata for PyPI distribution:

# From setup.py

license="GPLv3"

This dual documentation ensures that both source code users and package installers receive clear notice of the GPL-3.0 terms governing the software.

Understanding Copyleft Requirements

The GPL-3.0 is a strong copyleft license that grants users four essential freedoms: to run, study, modify, and distribute the software. However, these freedoms come with specific obligations regarding derivative works.

When you redistribute holehe or create modified versions, you must:

• License the derivative work under GPL-3.0
• Provide complete source code
• Include a copy of the GPL-3.0 license text
• State any significant changes made to the original codebase

This applies whether you distribute the standalone tool or integrate holehe modules into a larger application.

Practical Usage Scenarios

Installing from PyPI

You can install the tool under the GPL-3.0 terms using pip:

# Install holehe from PyPI

pip install holehe

# Run a simple check (e.g., test if an email exists on a service)

holehe -e example@example.com

Library Integration

When importing holehe as a Python library, the copyleft obligations still apply to your distributed application:

# Using holehe as a library

from holehe.modules.email import EmailModule

module = EmailModule()
result = module.check("example@example.com")
print(result)

If your project imports the EmailModule or other components from the holehe/ directory and you distribute the resulting application, your codebase must also be licensed under GPL-3.0.

Compliance Checklist for Developers

When working with the megadose/holehe codebase:

1. Include the License: Always ship the LICENSE.md file with any redistributed copies
2. Document Changes: Track modifications made to the core holehe/ directory source files
3. Source Availability: Provide access to the complete corresponding source code for any distributed binaries
4. License Compatibility: Ensure third-party dependencies are compatible with GPL-3.0 requirements

Summary

• The holehe project is explicitly licensed under GPL-3.0 as declared in LICENSE.md and setup.py
• The license is copyleft, requiring derivative works to use the same GPL-3.0 terms
• Users can install via pip install holehe or import from holehe.modules.email programmatically
• Redistributions must include the full license text and corresponding source code
• The LICENSE.md file at the repository root contains the complete GNU General Public License Version 3 text

Frequently Asked Questions

What license is holehe under?

The holehe project is released under the GNU General Public License v3 (GPL-3.0). The full license text is available in the LICENSE.md file, and the setup.py file confirms this classification with license="GPLv3".

Can I use holehe in commercial projects?

Yes, you can use holehe commercially, as GPL-3.0 permits commercial use. However, if you distribute the software or derivative works to others—including as part of a commercial product—you must release your source code under the same GPL-3.0 license terms.

Where is the license file located in the repository?

The license file is located at LICENSE.md in the repository root. This file contains the complete, unmodified text of the GNU General Public License Version 3, dated 29 June 2007.

Do I need to share my code if I modify holehe?

Yes. Under GPL-3.0 requirements, any distributed modified versions of holehe—or applications containing significant portions of the holehe/ source code—must be released under GPL-3.0 with complete source code provided to recipients.

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