F3 is an open source command-line tool that assesses the real capacity of USB sticks and other media. An advantage over other tools is, that it does not need administrative rights to access the device.


F3 vs H2testw Comments
Better than. Has same functionality (even can produce h2testw files) BUT HAS MORE. Probe facility to rapidly identify known fakes - much much quicker than h2testw. runs on macs as well as linux and doze. Open source. Brew designed to help learn techniques of fakery - if you are interested.
open source and being developed further


- F3 is Free and Open Source













it's open source and cross-platform