The Companion Proceedings of the 12th Brazilian Conference on Software: Theory and Practice (CBSoft 2021) bring the papers selected and presented in the edition of the event held online in Joinville, from September 27, 2021 to October 1, 2021. In this issue, the proceedings bring together the papers accepted and presented in four of the events integrated into the congress: Workshop on Theses and Dissertations (WTDSoft), Industry Track, Software Engineering Doctoral and Master Thesis Competition (CTD-ES) and Undergraduate Research on Software Engineering Competition (CTIC-ES). These papers were selected through a double-blind review. This volume was organized by Rodrigo Ribeiro (UFOP) – coordinator of WTDSoft; Alan Rafael Fachini (Magrathea) and Andreia Malucelli (PUCPR) – coordinators of Industry Track; Alfredo Goldman (USP) and Rossana Maria de Castro Andrade (UFC) – coordinators of the CTD-ES; and finally, Thelma Elita Colanzi (UEM) and Ivan Machado (UFBA) – coordinators of CTIC-ES.

For more information about CBSoft 2021, visit the website of the event.

To access the Proceedings of other events that are part of CBSoft 2021, visit the Proceedings of CBSoft.