What leaves your Mac
Exactly one thing: the text you selected when you triggered the Translator. It is sent over HTTPS to the Google Translate API. EIDevTools does not attach an account, a user ID, a device identifier, an installation token or any header that identifies you beyond what the operating system attaches to any HTTPS request. Google's terms apply to that request — EIDevTools is not their partner and has no business relationship with them.
What stays on your Mac
Everything else. Clipboard history is stored in the app's sandbox container. Snippets, password generator history (when not concealed), Pomodoro state, hotkey assignments and ignore-list rules live in standard preferences. If iCloud Drive sync is enabled, the relevant files are placed in iCloud Drive so that another Mac signed into the same Apple ID can read them — Apple's end-to-end encryption applies, EIDevTools never sees them in transit.
What is never recorded
The contents of any text field whose type is secure (NSSecureTextField) and any clipboard entry tagged as concealed by its source app (1Password, KeePassXC, Bitwarden, EIDevTools' own password generator, and others). They are intentionally excluded from clipboard history and never written to disk.
Required permissions
Two mandatory permissions. Accessibility — to read the currently selected text and to switch the keyboard layout (used by Layout Switcher, the Translator, Snippet Expander and the typing-mode of the password generator). Input Monitoring — to catch global hotkeys anywhere on the system. The app does not request Full Disk Access, Screen Recording, Camera, Microphone, Contacts or Calendars.
Contact
There is a Send Feedback button inside the app. It opens an email draft in your default mail client. The author reads everything sent to that address.