Local-first
Software that runs on your computer, not someone else’s.
Local-first software keeps your data on your device and treats the network as optional. Klar is built that way: every message is classified on your Mac, and the App Store build cannot reach the internet at all.
Get Klar freeThe idea
Cloud software borrows your data. Local-first does not.
Most of the software you use keeps your data on a company’s servers. That buys real convenience: it syncs across devices, and someone else runs the backups. It also means the things you made live somewhere you cannot see, under terms that can change, on a service that can be sold or shut down.
Local-first flips the default. Your data sits on your own machine, and the network is there when it helps rather than being the thing everything depends on. The term comes from a 2019 essay by Ink & Switch, which set out seven ideals for software that keeps people in control of their own data. For mail, ownership is the one that counts.
Read the Ink & Switch essayWhy mail is the hard case
A spam filter has to read your mail.
There is no way around that. A filter cannot judge a message it has not read, so the question that separates products is not whether your mail gets read, but where. Most filters answer: on our servers. You give a second company access to your mailbox and take its word on what happens next.
Klar answers: on your Mac. The model ships inside the app, and your mail is classified where it already lives. There is no server to trust because there is no server.
Where does your spam filter read your mail?How Klar holds to it
- No network access
- The App Store build ships without the network entitlement, and the Mail extension has none either. macOS refuses any connection they try to open. This is not a policy we promise to follow; it is a permission the app does not hold.
- The model ships with the app
- The classifier is a multilingual transformer inside the app bundle. Nothing is fetched when a message arrives, so Klar works the same on a plane as it does at your desk.
- No account
- There is nothing to sign up for. Install it, switch it on in Mail, and it filters. We do not know who you are.
- Learning stays on the device
- Move a message where it belongs and Klar Plus learns from it on the spot. The correction and the model it produces stay in a sandboxed container on your Mac.
- Open source engine
- The scoring engine is AGPLv3. You do not have to take our word for any of this. Read the code, build it, and check what it does.
Being precise
Where Klar does touch the network.
Local-first is a claim worth checking, so here is the whole list. The free App Store app never touches the network: it has no permission to. Klar Plus, which you install yourself, uses the network in two places. It checks your licence with our server, and it can pull model updates from our CDN.
Neither one carries your mail. Sending spam samples back to improve the filter is a separate switch, and it is off until you turn it on. Our servers are in the EU, and the only ones that exist are the website, the licence check and the model downloads.
Free, on the Mac App Store
Try a spam filter with no server.
macOS 14 or later, Apple Silicon. No account, no cloud, no setup.