The Felica IDm Reader App for RC-S380 is a versatile Chrome extension designed to read and write data from Felica cards, specifically the RC-S380 reader. This free tool enables users to read the IDm of Felica cards without needing native applications, allowing for seamless interactions with web pages through JSON messaging. It supports both Felica and Felica Lite-S cards, making it suitable for a variety of applications, including user ID management and card key writing.

Key functionalities include the ability to send a random challenge number and receive a response, alongside reading user IDs specifically for Felica Lite-S cards. The application requires the installation of the WinUSB driver for proper functionality, as it does not work with the default SONY drivers. Users should note that the app operates within the Chrome browser on Windows, and while it is tailored for Felica cards, it is not guaranteed to work on other operating systems or with different card types.