https://t.me/checklibot
(source: https://github.com/rayz1065/checkbot/commit/b5db5643631cd6792d5550118685410711614781)

A bot to create completely private checklists, together with a miniapp that makes editing these checklists with other people simple. The bot and mini-app can be used seamlessly in any chat, including groups, channels, pm with the bot, and with inline mode

Seems a bot, not a Mini-App..