I made a similar service [1] for sharing one-off secrets. The implementation is open-source [2] and the client consists of a single HTML page (about 250 lines)

I made a similar service [1] for sharing one-off secrets. The implementation is open-source [2] and the client consists of a single HTML page (about 250 lines) with no external links or resources which makes it easy to review. Nothing is sent to the server except the encrypted blob. [1] https://plic.ml https://plic.ml [2] https://github.com/mohd-akram/plic https://github.com/mohd-akram/plic