AmorphousDiskMark vs FFSB

AmorphousDiskMark is a free, open-source macOS utility for measuring storage read and write performance. It reports scores in megabytes per second or IOPS, with both units available in result tooltips. Sequential measurements use 1 MiB blocks, while random measurements use 4 KiB blocks; either type can run at queue depths from 1 through 1024. You can select random or zero test data, choose test sizes from 16 MiB to 64 GiB, and set intervals from 0 seconds to 10 minutes. Results can be copied as plain text, and the app can save a screenshot of its window. The product page lists macOS 10.9.5 or later, and the App Store describes it as Mac-only. The maker says an internet connection is unnecessary after downloading. The GitHub repository identifies an MIT license. The listed plan is free. Repeating read/write measurements may shorten storage-device lifespan.

FFSB has no write-up on Specifiction yet; its figures are above.