The use of this freely accessible web application is at your own risk. A guarantee or liability of any kind is expressly excluded.
The application runs completely clientside, no data is collected by me and no cookies are set by me. However, jquery 2.2.2, bootstrap 3.3.6, font-awesome 4.5.0 and json-editor are imported via a CDN.
Also, due to this web application being hosted on GitHub, I have no control over what data, e.g. IP and browser fingerprint, may or may not be logged by GitHub. 
Your entered username(s), password(s) and user data is processed locally in your browser and uploaded, by your browser, to the userspecified Lemmy instances. 
Due to the code running locally in your browser, passwords are temporarily saved and processed in cleartext by your browser.