In addressing the pandemic, contact tracing has been one of the most effective tools used worldwide. The use of these apps has caused several concerns, especially with regard to the protection of the privacy of individuals. While opinions largely differed with regard to the best technological solution to adopt, everybody agreed on the importance of one specific requirement: their full transparency. The idea that transparency can constitute a valid safeguard for the correct, secure and lawful use of digital applications is then analyzed as a constitutional value to uphold. This work aims at investigating how transparency has been translated from theory to practice and follows its constitutionalization process in a post-pandemic world. It finally asks whether there is anything one can learn from the experience with contact tracing apps in order to create a suitable model for the public governance of algorithms.