Using with KiCad

Requirements

The current FreeRouting program is the native C++ binary freeRouting. The easiest way to get it is the LayoutEditor package; freeRouting is in the bin folder of that package. No Java runtime is required.

Alternatively you can build FreeRouting from source with qmake and make. See also Getting FreeRouting.

Usage

Work in the KiCad PCB Editor (Pcbnew), not in the schematic editor. Current KiCad releases (including KiCad 8 and 9) exchange Specctra files from the File menu:

• File → Export → Specctra DSN (some builds label it Spectra DSN) writes the board for the router,
• after routing, File → Import → Specctra Session reads the ses file back onto the board.

Open the exported dsn in freeRouting, run Autorouting (or route interactively), then write a Specctra session from File → Export → Export Specctra Session File. Import that ses in KiCad.

Place footprints and draw the board outline before the export. The router follows the copper layers, nets and rules that KiCad wrote into the dsn. After the import, check the board in KiCad: vias and tracks from the session are merged into the PCB.

Older KiCad versions offered a dedicated autorouter dialog from a toolbar button. That path is gone in current Pcbnew. The videos below show earlier screens; the dsn / ses round trip is the same idea.

There are some Youtube videos explaining it in detail: