There is no free bootstrap theme available. But Dude Theme is LESS BOOTSTRAP and looking nice but its not free and doesn't know if it is compatiable to Q2A version: 1.6.3
Otherwise you can integrate bootstrap theme on q2a platform.Now I have created my own bootstrap theme with new layout
Cleanstrap: free, open source and responsive.
Uses bootstrap (proof: https://github.com/Towhidn/CleanStrap/blob/master/cleanstrap/js/bootstrap.js)
Compatible with 1.6.3, I used it for a few months on 1.6 no problems.
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.
July 15, 2020: Q2A 1.8.5 released!