In high school I built a chrome extension to secretly chat with my girlfriend on the Google Search page.

Her parents were super strict and would not allow having a boyfriend, we were caught once so wanted to be few steps ahead of their detection.

Using internet was allowed for her to study. Made the extension such that when you search for something popular click on the largest image in knowledge graph (right side box) 4 times and then do a right click the wikipedia description will become a chat box (to avoid accidental discovery by her sister).

Backend a very simple .txt file and php to insert and maintain only last 5 conversations.

I think I made it over a few days. We used it for a total of 2 times because we couldn’t notify each other when we come online.

Switched to a simple ROT13 encoded sms-ing. With the key changing every day.