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Fierce vs Findomain: catalog facts
Fierce	Findomain
Free Free and open source under the GPL-3.0 license.	Freemium A free version is available, with some features reserved for the premium version.
Command line	Command line
Finds hostnames and related IP space through DNS reconnaissance Can traverse nearby IP addresses	Finds subdomains from Certificate Transparency logs and APIs Supports monitoring alerts through chat services
Intended for authorized testing Command-line interface only	Some features are available only in the premium version.
Downloadable app	Downloadable app
Open source	Open source
License: GPL-3.0	License: GPL-3.0
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked October 8, 2026	Official website Full listing and sources Checked October 8, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.