SlowInk is a digital pen pal application designed for slow letter writing and meaningful asynchronous communication. The app focuses on recreating the experience of traditional postal correspondence by introducing real delivery delays, where messages arrive over time rather than instantly. Users can write and exchange letters with matched pen pals based on shared interests and geographic regions, fostering low-pressure social connections that emphasize reflection and anticipation. The application includes several core features. A pen pal matching system pairs users according to their preferences and locations. A stamp collection and boost mechanism allows users to collect virtual stamps that can shorten the wait time for specific letters when needed. A stamp album tracks collected stamps and rewards, while a world places feature provides destination inspiration for letter content. Time capsules enable users to write letters to their future selves or friends, which become available at a predetermined date. The delivery system operates on real elapsed time, with the distance between sender and recipient influencing the overall wait and reveal. Typical use follows a three-step workflow: the user selects a recipient and writes a letter, then chooses stamps to set the delivery speed and mood of the send off. The app supports both one to one exchanges and self addressed time capsules. It also includes privacy settings, a privacy policy, terms of service, and child safety standards. SlowInk is available for download directly from its website and functions as a mobile application, though no specific platform or technical requirements are listed. The app is presented in both English and Chinese, with the tagline referencing the slower pace of traditional mail.