About
Hearth for Windows is a desktop application for running language models on your own hardware and pointing an autonomous coding agent at your own files. It installs per-user, carries its own interpreter and its own inference engine, and does not require an account, a subscription, or a network connection to do the part it exists to do.
Two projects share this name
That is worth stating plainly, because it causes confusion otherwise.
hearth is a security-first NixOS system: a whole reproducible operating system configuration where local models and agents run sandboxed by default, every run is audited, and system state is legible from boot. It is a Linux thing, and it expects you to be comfortable with Linux.
Hearth for Windows, this project, is a desktop application. It shares an engine lineage with the NixOS system and a good deal of code, but it is installed by double-clicking an installer and used by opening a window.
The documentation sites are deliberately the same shape and deliberately different colours: orange for the NixOS system, blue for this one. If you are ever unsure which set of docs you have open, the colour answers it faster than the URL does.
Where the two differ in what they can promise, the Windows documentation says so rather than borrowing the stronger claim. The threat model and limitations pages both name protections that exist on NixOS and do not exist here.
Where the documentation lives
The pages on this site are published from the docs/ directory of the
repository, by site/port_docs.py. The repository is the source of truth: a
person reading the code on GitHub should not have to visit a website to learn
how the thing works, and a person reading the website should not be reading
something that has quietly drifted from the code.
If a page here looks wrong, the file to fix is under
docs/, and
the “Edit page” link at the bottom of each page goes to the right place.
Licence
Apache-2.0, including the patent grant in section 3. See Licensing for how that interacts with the vendored components, and THIRD-PARTY-NOTICES.md for the generated list of everything that ships inside the installer.
There is no separate CLA. Section 5 of the licence already covers a contribution offered under its terms.
Reporting problems
Bugs and feature requests go in GitHub issues.
Anything security-sensitive should go through the security policy instead of a public issue. Reports about the release signing key or the update channel should say so in the first line: those are the two places where a problem reaches every install at once.
Credit
Built by Eric Catalano.
The parts that are not mine are listed, with their licences, in THIRD-PARTY-NOTICES.md. That file is generated from what is actually on disk at build time and is never written by hand, and CI fails the build when it goes stale.