Jo is a voice assistant for getting through email, meetings, and follow-ups while the phone stays in a pocket. It is open source and built for people whose work happens while they are moving or hands-busy, including runs, commutes, yoga, cooking, and laundry. The public release follows months of testing with users. The announcement says the builders do not see your data or the tool calls, and that local-first models keep data on the phone. The native iOS app also includes a watch companion and a Live Activity. In a call, Jo reads the week ranked by what matters, then summarizes, drafts, and sends replies, archives, labels, and unsubscribes, and writes to the calendar. Longer jobs move to a background worker so the conversation can continue. From the phone it talks directly to Gmail, Google Calendar, Slack, GitHub, Notion, Granola, and any custom MCP server you add, with credentials held in the Keychain. Ranking and decisions run on the device, using your own OpenAI key by default. A local voice model can be downloaded once, there is no analytics or telemetry, and a thin Google token shim handles sign-in without storing mail. Nate Tucker, previously founder of StartPlaying, announced Jo after he moved fundraising off video calls and wanted a way to do that work by voice. The MIT-licensed repository includes a skill file so Claude or ChatGPT can help with install, either by downloading the app or loading it onto a phone.