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Fierce vs DNSRecon: catalog facts
Fierce	DNSRecon
Free Free and open source under the GPL-3.0 license.	Free Free and open source.
Command line	Windows, macOS, Linux, Command line
Finds hostnames and related IP space through DNS reconnaissance Can traverse nearby IP addresses	Covers record lookups, zone transfer tests and subdomain brute-forcing Can run in Docker
Intended for authorized testing Command-line interface only	Intended for authorized testing only Command-line only with no graphical interface
Downloadable app	Downloadable app
Open source	Open source
License: GPL-3.0	License not stated
Not stated if an account is needed	No account needed
Not stated if it works offline	Needs internet
Official website Full listing and sources Checked October 8, 2026	Official website Full listing and sources Checked September 24, 2026

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