• Offline by design. CalcDex has no accounts, no telemetry, no analytics and no crash reporting. The single network feature is the update check: off by default, and even when on (or run by hand with --check-update) it only reads the latest release version from GitHub and downloads nothing — anything it offers is fetched by you, from the release page.
• Your data stays yours. Settings, the calculation log and saved examples are plain-text files in one place (the data folder beside the executable, see MIGRATION.md). Nothing is uploaded or synced anywhere.
• No privileges. The program runs without administrator rights and the installer is per-user.
• Input is untrusted. Calculator inputs and the contents of the data files are validated as they are parsed; bad input produces a plain-words error, not a crash. Data-file saves are atomic (write to a temporary file, flush, rename over), so an interrupted save cannot corrupt the previous file.
• Unsigned builds. Release binaries are not code-signed. Verify downloads against SHA256SUMS.txt on the release page (see INSTALL.md).

Please report suspected security problems privately through GitHub's security advisory flow on the repository (https://github.com/SeanShaffer88/CalcDex/security/advisories) rather than as a public issue.