PurposeThe purpose of this study is to analyse and discuss K-12 mathematics and technology teachers' perceptions on integrating programming in their teaching and learning activities, and perceptions on different programming tools.Design/methodology/approachThe approach of a case study was used, with data collected from three instances of a professional development programming course for K-12 teachers in mathematics and technology.FindingsThe findings show that there are perceived challenges and opportunities with learning and integrating programming, and with different programming tools. Many teachers perceive programming as fun, but lack the time to learn and implement it, and view different programming tools as both complementary to each other and with individual opportunities and challenges.Practical implicationsThe practical implication of the research is that it can provide guidance for teachers and other stakeholders that are in the process of integrating programming in K-12 education. Further, the research provides useful information on teachers' experiences on working with different programming tools.Social implicationsThe social implication of the research is that the overall aim of the nation-wide integration process might not succeed if the challenges identified in this study are not addressed, which could have negative effects on the development of students' digital competence.Originality/valueThe value of the research is that it identifies important challenges and opportunities for the integration of programming. That is, that many teachers perceive the different programming tools available as complimentary to each other, but are hesitating about what is expected of the integration. Findings could also be valuable for future course design of the teacher professional development.