fosforo

2026-10-08 · github.com/crgimenes/fosforo

fosforo is a terminal emulator for macOS, iPadOS and iOS, written in C and Swift and drawn with Metal.

On the Mac it is a fast terminal made for developers: your login shell on a pty, with the system’s ssh and git, several sessions per window, search, copy mode and shell integration.

On the iPad and iPhone the shell is rocchetto, built into the app: pipes, redirects, functions, history, and sixty-odd commands written in Filo. The ssh and mosh commands are the app’s own clients, and private keys can be kept encrypted by a key in the device’s Secure Enclave, opened with Face ID, Touch ID or the passcode.

Configuration and themes are Filo scripts. The default font is IBM 3270; box drawing, blocks, braille and Powerline glyphs are drawn from geometry, so ANSI art has no seams.

The Mac app is signed and notarized, for Apple silicon and Intel (brew install --cask crgimenes/tap/fosforo). The iPad and iPhone app is free on the App Store. MIT licensed.

Privacy

fosforo collects no data. It has no analytics, no crash reporting, no advertising and no accounts; nothing is sent to its author or to any partner.

• The app connects only to the machines you name, or that a program you run asks for: what an SSH or Mosh session carries goes to that server, encrypted.
• Files you put in the app’s iCloud Drive folder (~/iCloud) are stored by Apple in your own iCloud account; the rest of the home, ~/.ssh and ~/.config included, stays on the device.
• SSH keys live in ~/.ssh inside the app, readable by no other app on the device (mode 0600, the strictest file protection iOS offers) and left out of device backups, so they do not travel to a new device. A computer the device trusts can copy the app’s files, keys included, as it can any app’s: key protect is what keeps a key sealed even then. A key is a plain file until you run key protect: then it is sealed by this device’s Secure Enclave and each use asks for Face ID, Touch ID or the passcode; the app never sees biometric data. On a device with no passcode the seal still works, but nothing is asked; the app says so.
• Removing the app removes everything it stored on the device; files in your iCloud Drive folder stay there until you delete them.

Questions about privacy: open an issue.

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