Zero
Experience email the way you want with Mail0 – the first open source email app that puts your privacy and safety first. Join the discord: https://mail0.link/discord
A self-hosted, privacy-first open-source email client that connects to Gmail and Outlook accounts in a unified inbox, with AI features and full control over where your data lives.
Zero is an open-source email application built as an alternative to Gmail and similar services. Its main emphasis is privacy: the project states it does not track, collect, or sell user data in any way. Because the source code is publicly available, anyone can inspect how the application works and verify those claims for themselves.
The application connects to external email providers like Gmail and Outlook through their official APIs and presents all of your accounts together in a single unified inbox. It also includes AI features described as agents and language model integrations, though the README focuses more on setup instructions than on what the AI capabilities actually do in practice. The project is self-hosted, meaning you run the application on your own server or computer rather than accessing it through a shared service. That gives you full control over where your email data is stored and processed.
The technology stack is built on Next.js and React for the user interface, with a Node.js backend, PostgreSQL for storing application data, and standard authentication through Google OAuth. Setting it up locally requires installing Node.js, a package manager called pnpm, and Docker (a tool that runs software in isolated containers). The setup process involves cloning the repository, running a helper command to configure environment variables, starting a local database container, and then launching the development server. Connecting Gmail specifically requires creating credentials in Google Cloud Console, which involves enabling two APIs and setting up an OAuth application, a process the README walks through step by step.
Optional integrations mentioned in the setup section include a service called Autumn for encryption and Twilio for SMS functionality. Both require creating accounts with those third-party services and adding API keys to a configuration file.
The project welcomes contributions and has a community Discord server. It is positioned as a developer-friendly foundation that others can extend with additional integrations and customizations.
Where it fits
- Self-host a privacy-respecting email client on your own server so your email data never passes through a third-party service
- Combine multiple Gmail and Outlook accounts into a single unified inbox with AI-assisted features
- Extend the open-source codebase with custom integrations and email workflow automations
- Use it as a foundation for building a privacy-focused email product or SaaS application