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Siege vs Fortio: catalog facts
Siege	Fortio
Free Free and open source.	Free Free to use, with the source code published on GitHub.
macOS, Linux, Command line	Web, Self-hosted, Command line
Tests many URLs at once from a list Configurable number of simulated users	Fixed queries-per-second load for repeatable tests Latency histograms and detailed statistics
Command line only, with no graphical reports Scripting options are simpler than in newer load testers	Aimed at developers and operators rather than casual users Measures servers under load, not page rendering speed
Downloadable app	Downloadable app, Self-hosted
Open source	Closed source
License: GPL-3.0	License not stated
No account needed	No account needed
Works offline	Works offline
Official website Full listing and sources Checked September 24, 2026	Official website Full listing and sources Checked October 2, 2026

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