Mozilla's for-profit arm MZLA — best known for maintaining Thunderbird — launched Thunderbolt on April 16, an open-source AI client aimed at businesses uncomfortable with the data lock-in of Microsoft Copilot, ChatGPT Enterprise, and Claude Enterprise. Thunderbolt is pitched as a 'sovereign AI workspace': organizations can plug in any model (commercial, open-source, or local), connect internal data through deepset's Haystack and Model Context Protocol (MCP) servers, and automate repeatable workflows. It ships as a web app plus native builds for Windows, macOS, Linux, iOS, and Android, all licensed under MPL 2.0 and hosted on GitHub. The pitch is control: run your own models, on your own servers, with your own data. It puts self-hosted AI back on the table for enterprises worried about privacy and vendor lock-in.