Priit Kasesalu

Co-developer of Skype and head programmer for Kazaa Media Desktop, Kasesalu is a pioneering Estonian software developer. In 1986, he began his career as a programmer for a local hardware manufacturer with his classmate Jaan Tallinn. The company was assembling 8-bit computers for use in public schools. He wrote various software for the platform, including several games. In 1989, together with Ahti Heinla and Jaan Tallinn, he participated in creating Kosmonaut—the first Estonian computer game to be published outside the country. He studied Computer Science in 1992 at Tallinn Technical University.

Kasesalu has played an integral role in developing Kazaa and later Skype along with Ahti Heinla and Jaan Tallinn. He has also served as a core library developer at Skype. While cryptography and data communication were his areas of expertise, his other passion has been computer game development. In addition to the computer game Kosmonaut, he created Continuum and BanG, and edited subgame2. Kasesalu is also noted for having been a head programmer for Kazaa Media Desktop.

Skype was first released in 2003 and developed into a platform with over 600 million users, and was bought by Microsoft in 2011 for $8.5 billion. The service allows users to communicate with peers by voice using a microphone, video by using a webcam, and instant messaging over the Internet. Phone calls may be placed to recipients on the traditional telephone networks. Calls to other users within the Skype service are free of charge, while calls to landline telephones and mobile phones are charged via a debit-based user account system.

Skype also became popular for its additional features, including file transfer and videoconferencing. Competitors include SIP and H.323-based services, such as Linphone and Google Voice. The network is operated by Microsoft, which has its Skype division headquarters in Luxembourg. Most of the development team and 44% of the overall employees of the division are situated in Tallinn and Tartu, Estonia.

At the time of his work with Ambient Sound Investments (ASI), Kasesalu was heavily involved in assessing all of ASI's new technology investments. He also set up Bluemoon Software with Ahti Heinla and Jaan Tallinn, and has been involved in most of the projects of the company.