The Sigil Generator aka Web App does not store or send your inputs anywhere, it’s completely private. All the custom code runs client-side (in your browser) which can be verified with a debugging console. The only parts of that tool making outside calls are just the standard Google snippets (see below) and some imported fonts (see below).
Standard Google Snippets
The site uses a few snippets of Google code:
Google Analytics: Basically let’s me know how much traffic I’m getting.
Google AdSense: Shows advertisements.
Visitors: If you are just visiting, I’m not collecting any data about you besides traffic etc (see Google Snippets, above)
Users: If you log in as an author here I only have whatever data you provide for creating an account, IP Address, and Google Snippets (see above)
Comments: If you leave a comment I only have whatever data you provide in the comment form, IP Address, and Google Snippets (see above)
IP address: I don’t use this for anything besides blocking abusive users.
Email address: If you provide an email address on my site I don’t use it for anything unless you ask me to contact you. The site uses it to help reset your password if you forget it.
All Other Info: I don’t do anything with any personal info you provide (name, hobbies, etc).
Cookies: Some standard site-functionality cookies are used for log ins and comments.
Some Google Fonts and Font Awesome are imported for both the Main Site, and the Sigil Generator. You may notice these external calls. It is only for display purposes/typeset.