subfinder – subdomain discovery tool

subfinder is a subdomain discovery tool that returns valid subdomains for websites, using passive online sources. It has a simple, modular architecture and is optimized for speed. subfinder is built for doing one thing only – passive subdomain enumeration, and it does that very well.

This is free and open source software.

Features include:

• Fast and powerful resolution and wildcard elimination modules.
• Curated passive sources to maximize results.
• Multiple output formats supported (JSON, file, stdout).
• Optimized for speed and lightweight on resources.
• STDIN/OUT support enables easy integration into workflows.

Website: github.com/projectdiscovery/subfinder
Support:
Developer: ProjectDiscovery, Inc.
License: MIT License

subfinder is written in Go. Learn Go with our recommended free books and free tutorials.

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