Measuring open innovation practices in small companies at important Brazilian industrial centers

•The article focuses on concepts and practices of innovation, OI and possible indicators for small Brazilian companies.•Using the "survey" methodology, many OI practices were clearly identified in respondent companies.•With OI, companies share more information about products, services, and processes.•The proposed indicators were tested and approved by the statistical technique "Factor Analysis".•Researchers and interested managers can start or increase their own OI practices.