What is simjiang?

SimJiang is a free Android app for managing SIM and eSIM phone numbers. It is written in Kotlin and aimed at people who hold multiple phone numbers across different carriers or countries and need to keep track of when each number expires or needs activity to stay active. The app stores details for each number including the country, area code, operator, expiry date, and the schedule for keeping the number alive. Users can set up reminders delivered as local phone notifications, Telegram messages, or email via SMTP. There is also a cloud reminder service where the server checks expiry dates on a schedule and sends alerts, with data separated by API key so multiple users can share the same server without seeing each other's records. Other features include a real download test for checking data speeds, import and export of number records in JSON or CSV format, and support for light and dark themes with optional custom backgrounds. The interface is available in Simplified Chinese, Traditional Chinese, English, Japanese, and Arabic. The README is brief and written primarily in Chinese. It lists the core features and provides the default cloud reminder server address along with build instructions for compiling from source. The project includes the server-side code for the reminder service in the repository under a separate directory.