Viaduct Desktop
Viaduct on your own machine.
The whole editor as a native app for macOS, Windows and Linux — all four C4 levels, Magic flows, docs, sequences and contracts, with an MCP server running on localhost so Cursor and Claude Code read the same model. Projects are plain JSON files in a folder you choose.
Debian and Ubuntu, 64-bit · DEB · free for 7 days
macOS
Apple Silicon (M1 and later)
Download DMGWindows
64-bit (x64)
Download EXELinuxYour system
Debian and Ubuntu, 64-bit
Download DEB
7 days freethen €10 a month
The trial starts the first time you open the app — no card, no account. After that a licence key keeps it running, billed monthly and cancelled whenever you like.
Subscribe- 7 days free, no card asked for
- Projects are JSON files you own
- MCP server built in, on 127.0.0.1
- One licence covers 3 machines
- Works offline between checks
The builds are not code-signed yet: on macOS, right-click the app and choose Open the first time. Viaduct in the browser stays free — the subscription is the desktop app.
Before you install
What does it cost?
Free for 7 days on each machine — no card and no account to create. After that a licence key keeps it running, €10 a month, billed monthly and cancelled whenever you like.
How many machines does one licence cover?
3. An activated copy also keeps working with no network at all: it re-checks the licence every 7 days, and between those checks a flight or an air-gapped office changes nothing.
macOS says the app cannot be opened. Why?
The builds are not code-signed yet. Right-click the app and choose Open the first time, and macOS remembers the decision. Signing is on the list; until then this is the honest answer rather than a workaround buried in a support thread.
Do I need the desktop app at all?
No. Viaduct in the browser is free and gives you the whole model, including the hosted MCP server once you sign in. The desktop app is for the case where the architecture cannot leave the machine — or where you would simply rather it did not.