Inspect or build it yourself
You don't have to take our word for what Basil does. Basil is open source under the Apache-2.0 license, so anyone can read it.
Read it
All of it's in one repo.
The Mac app, the local backend, and the windows you saw on this site are all in the repository. The windows on the home page are the app's own interface code, copied into this site at a recorded commit.
If you're deciding where to point Basil, the privacy and data flow guide lists what stays on your Mac and what leaves it for each model choice.
Check it
Confirm that a download matches the code.
Every update to the main branch is built on GitHub's own machines, signed, notarized by Apple, and published with a build-provenance record. You can check that a file you downloaded is exactly the file that build produced, and see which commit it came from.
The verifying builds guide walks through it step by step: compare the checksum, then ask GitHub to verify the attestation. It also lists what the check proves and what it doesn't. In particular, builds aren't reproducible byte for byte, and the attestation isn't a security review.
The download on this site is published separately by us. It contains the same code, but the guide applies to the builds published on the repository's Releases page.
Build it
Or skip the download and make your own.
The getting started guide covers what you need and how to build and run Basil on a Mac. It's a developer setup, with Xcode or just the Swift toolchain, plus Python, Poetry, Node, and Homebrew, so it's meant for people comfortable in a terminal.
The repository doesn't include model files or provider keys. You add those on your own machine after you choose a model.