Castellan for Windows
Local AI, on duty.
A staff of AI agents that runs your PC and your projects, and works through the day without being asked. It runs on your NPU, GPU or CPU. On an NPU it's fastest, coolest and lightest on the battery.
Your AI. Your data. Your PC.
Best on an NPU. Great on a GPU. Works on any CPU.
Local AI, on duty
A staff of AI agents that runs your PC and your projects, and works through the day without being asked. It runs on your NPU, GPU or CPU. On an NPU it's fastest, coolest and lightest on the battery.
Your AI. Your data. Your PC.
Your AI runs on your PC, and your files never leave it. No cloud AI, no uploads, no one reading your documents, photos or code.
Spend less on cloud AI
Reeve does the heavy reading on your own hardware: build logs, test runs, code searches. Your AI coding assistant gets the few lines that matter. Fewer tokens, smaller bills, and usage limits that last longer.
The staff
A household for your PC
On a manor, each office had its officer: the porter at the gate, the clerk with the rolls, the lamplighter on the lanes. Castellan fills each office with an agent.
Smith
Keeps the local AI running: the model servers every agent works from.
Porter
What's new on your PC, who signed it, and whether it matches.
Thatcher
Keeps your installed apps in repair.
Reeve
The local helper for your AI coding assistant, and rounds on your repositories.
Clerk
Makes your screenshots and scans searchable.
Chamberlain
Your documents and mail, indexed on your PC, and answers about them.
Herald
The news you follow, summed up.
Warrener
A name and a home for what piles up in Downloads and on the Desktop.
Miller
Big videos and photos, made small.
Meet every agent · and Heiward, free: Finds duplicate photos and videos, and stale developer files.
How it works
Three steps, then it runs itself
Step 1
Install Castellan
One setup, no administrator rights, nothing else to install first. It brings its own runtime.
Step 2
Hire your staff
Each office on the page offers Hire. Take the ones you want: the photos and videos staff, the gate-keeper, the driver-watcher, the developer roles.
Step 3
Let them work
They work on their own, within what you allow: anything that changes your files or your PC waits for your tick.
The Freehold licence
Every version you've paid for is yours to keep.
Stop paying and nothing stops working: the agents you have keep running, for good. You can still download, on any of your PCs, any release published while you paid. You simply stop getting new releases until you subscribe again, and then you catch up at once.
Questions
Asked often
Do I need an NPU?
No. Castellan runs its AI on your NPU, your GPU or your CPU. An NPU (Snapdragon X, Intel Core Ultra or AMD Ryzen AI) is the best of the three: fastest, coolest and lightest on the battery.
Does anything I have leave my PC?
Your files don't, and the AI runs on your PC. Castellan goes online to check your licence and fetch updates, and some agents fetch what you ask them for (the Herald's news, Reeve's repositories). The privacy notice lists every one.
What happens if I stop paying?
Nothing stops working. Every version you paid for is yours to keep: the agents you have keep running, for good, and you can reinstall them. You stop getting new versions until you subscribe again, and then you catch up at once.
How many PCs?
Up to 3 per licence. A PC gives its place back from Settings, and another can take it.
Is there a trial?
7 days of everything, with no card, once per PC.