How Leon Handles Privacy and Data Control

Leon is an open-source personal assistant that runs on your own server, and that single design decision answers most privacy questions up front: your data stays on infrastructure you control, and you decide whether any third-party service ever sees it. If you want an assistant you can self-host and inspect, Leon is built for exactly that. If you'd rather not run a server or manage Node.js and Python yourself, the self-hosted model is the main trade-off to weigh.

Where your data actually lives

Leon "lives on your server." That means conversations, skills, and any data a skill processes are handled on hardware you provision, not on a vendor's cloud by default. The site states plainly: "You are in control of your data. Leon lives on your server and you decide if you wish to make use of any third party."

The practical consequence is that privacy is a configuration choice, not a promise you have to trust. Two things follow from that:

• Default posture: nothing leaves your server unless a skill or integration you enable sends it somewhere.
• Your responsibility: because you control the server, you also control backups, access, and network exposure. Self-hosting shifts privacy control to you, and so does the operational burden.

The open-source guarantee

Leon is released under the MIT license, described on the site as "the most permissive license in the open-source world." For privacy specifically, this matters because you can read the code, verify what it does with data, and modify it if you disagree with a behavior. You aren't relying on a vendor's description of its own data handling.

MIT also means you can fork, extend, or strip out components without restriction — useful if you want to remove a third-party integration entirely rather than just disable it.

Third-party services are opt-in, not baked in

Leon supports several cloud speech services, but the site frames them as choices you make, not defaults. The available options:

The key privacy point: offline options exist for both directions. If you use CMU Flite for TTS and Coqui STT for STT, voice data doesn't need to reach a cloud provider at all. If you pick a cloud service, you're explicitly opting into sending that audio to that provider — a decision the architecture leaves to you.

Modularity limits your exposure surface

Leon uses a modular architecture where functionality comes from packages/modules called "skills." You install only the skills you need. Fewer skills means fewer integrations that could transmit data outward, and each skill can be inspected before you enable it. The site describes this as "no barrier, only an infinity of possibilities" — but from a privacy standpoint, the useful reading is that you can keep the footprint small.

What to check before you commit

Because the site doesn't publish a data-handling policy beyond the self-hosted model, verify these yourself:

1. Which skills you enable — each may have its own external dependencies.
2. Which speech services you configure — cloud options send audio to that provider; offline options don't.
3. Your server's security — since Leon runs on your infrastructure, its privacy is only as good as your server's access controls.

If self-hosting and inspecting the code fit how you want to handle your data, Leon's model gives you direct control. If you need a managed service with a vendor-held privacy policy, this isn't that — and the site doesn't claim otherwise.