# Does Teensy work on macOS 28?

> **Short answer: no, not on its own.** According to Homebrew’s package data (checked October 5, 2026), Teensy is Intel-only and its current download has no Apple silicon build. Apple says Intel-only apps stop running on Apple silicon Macs after macOS 27, apart from some older games. Keep86 is built to keep apps like this running, but we haven’t tested Teensy yet.

## Key facts

- Architecture: Intel-only (according to Homebrew’s package data, checked October 5, 2026)
- Homebrew package: teensy (https://formulae.brew.sh/cask/teensy), 90 installs in the last 365 days
- Website: https://pjrc.com/teensy/loader_mac.html
- Native Apple silicon version: None listed
- Keep86 status: Not tested yet
- Latest known version: 1.59-beta3
- Last verified: 2026-10-05

## Questions about Teensy

### Does Teensy work on Apple silicon?

Only through Rosetta 2. Teensy is Intel-only: an Apple silicon Mac runs it by translating its Intel code with Rosetta 2, which Apple supports in full until macOS 27.

### Does Teensy need Rosetta 2?

Yes, on every Apple silicon Mac. Apple has said that from macOS 28 Rosetta remains only for some older games, so Intel-only apps like Teensy stop opening.

### How can I keep using Teensy after macOS 28?

Stay on macOS 27 on this Mac, switch to an alternative, or run Teensy in a macOS 27 virtual machine (UTM, VirtualBuddy, Parallels). Keep86 runs that virtual Mac hidden and shows the app’s windows on your desktop; see the test status above.

## Sources

- Homebrew cask “teensy” 1.59-beta3 requires Rosetta (Intel-only build) — https://formulae.brew.sh/cask/teensy (2026-10-05)

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Architecture data partly from Homebrew (formulae.brew.sh), used under the BSD 2-Clause licence.
Source: https://keep86.com/apps/teensy