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GNU Grep vs ack: catalog facts
GNU Grep	ack
Free Free software from the GNU Project with no paid tier.	Free Free and open source.
Linux, Command line	Windows, macOS, Linux, Command line
Installed by default on most Linux systems Thorough documentation via man, info and online manual	Built for searching source code rather than general text Full Perl regular expressions
Slower on large codebases than tools like ripgrep or ugrep Does not skip ignored files or directories by default	Needs a Perl interpreter Newer tools such as ripgrep are typically faster on very large trees
Downloadable app	Downloadable app
Open source	Open source
License: GPL-3.0-or-later	License: Artistic-2.0
No account needed	No account needed
Works offline	Works offline
Official website Full listing and sources Checked October 1, 2026	Official website Full listing and sources Checked September 23, 2026

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