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Run more iOS simulators on one Mac.

A stock iOS simulator starts around 180 background services that development, testing and CI never use. simslim switches them off, so each simulator needs about a quarter of the memory.

GitHubRead the story
~ % simslim list
E20DA160…  iPhone 17 Pro      iOS 26.5  booted · 170/170 slim
4EEF686E…  iPhone 18 Pro      iOS 27.0  shutdown
E93AEF04…  iPhone 18 Pro Max  iOS 27.0  shutdown
9C0556EA…  iPhone Duo         iOS 27.1  shutdown

~ % simslim measure E20DA160…
E20DA160…: 62 processes, 952 MB memory footprint (phys_footprint)
why

A screenful of simulators, not a handful

  • 4.0 GB → 0.9 GB per simulator, 258 → 70 processes
  • 12 simulators on a 16 GB Mac, up to 19 in our tests
  • One command per simulator, and simslim off puts it back to stock
  • Keep what your tests need with --except or --keep
  • Works in CI: the mobai-ci GitHub Action slims its simulator for you
get started

Get started

bash
brew install mobai-app/tap/simslim
bash
simslim on <udid>

Fit more simulators on the Mac you have.

simslim on GitHubRun every phone at once →