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cFIREsim vs FIRECalc: catalog facts
cFIREsim	FIRECalc
Free Free to use in the browser.	Free Free to use on the web; no paid tier is mentioned.
Web	Web
Tests withdrawal plans against historical data Runs in the browser with nothing to install	Tests plans against every historical start year since 1871 Shows worst-case outcomes rather than averages
Focused on US retirement planning Detailed tax modelling lives on the separate FIREproof site	Assumes future markets resemble the past Plain, dated interface
Web application	Web application
Closed source	Closed source
License not stated	License not stated
Not stated if an account is needed	No account needed
Needs internet	Needs internet
Official website Full listing and sources Checked October 2, 2026	Official website Full listing and sources Checked September 24, 2026

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