Chaser

flywire

Point-to-point wiring for building a KiCad board by hand: wire wrap, fly wires on a perfboard, or a carrier without copper. flywire reads the placed .kicad_pcb, joins every net's through-hole pins with one wire per pair of pins, bends the wires so they keep off other pads and off each other, and writes:

• wiring.html: one self-contained interactive page (no network needed, like InteractiveHtmlBom): the board seen from the back with the wires as curves, and the wire list beside it;
• wiring.txt: the same wire list as text, with pin positions, lengths, cut lengths and the wires per pin (which to wrap first);
• wiring.json: the wiring, in the form the page exports and --edits reads back.

Copper tracks and zones are ignored; SMD pads are too (they do not reach the back).

Demo: existedinnettw.github.io/flywire, the page for examples/chaser (a 555 clocking a CD4017 that walks four LEDs), rebuilt by the pages workflow on every push to main (wiring.txt, wiring.json, chaser.kicad_pcb).

use

uv tool install git+https://github.com/existedinnettw/flywire   # or: uvx --from ... flywire
flywire board.kicad_pcb                      # build/wiring.html, .txt, .json
flywire board.kicad_pcb --max-per-pin 3      # trees instead of chains
flywire board.kicad_pcb --edits wiring.json  # with what you changed on the page

The exit status is 1 when the wiring has problems (a net in pieces, a pin over the limit); they are listed at the end of wiring.txt.

the page

• Wheel zooms, drag pans, double-click fits; Back / Front (F) flips the view (the back, where the wires are, is the default: x is mirrored).
• Click a wire or a row to select it, a pin to show its net; ↑ ↓ step through the list, Space ticks a wire done (kept in the browser, per board), Hide done hides them.
• Edit (E):
  • drag a wire's round handle to bend it;
  • drag a square end handle onto another pin of the same net to reconnect it;
  • click a pin, then another pin of its net, to add a wire;
  • Del deletes, A bends automatically, S straightens, Ctrl+Z undoes;
  • Auto-bend bends again every wire not bent by hand; Reset goes back to the proposal.
• The box above the list says when a net falls apart or a pin takes too many wires.
• Export downloads wiring.json; flywire board.kicad_pcb --edits wiring.json rebuilds the text list and the page with your changes, so they can be committed with the board.

how the wires are bent

Each wire is a quadratic Bézier from pin to pin, given by the point half way along it. For every wire a set of such midpoints, pushed sideways and along the chord, is priced: samples of the curve inside a foreign pad's clearance, near another wire (a crossing costs little, a wire lying along another a lot, except near a pin both end at), outside the board, and the extra length. The longest wires go first, then every wire is placed again against all the others until nothing changes. src/flywire/bend.py is the reference; src/flywire/web/bend.js is the same algorithm for the page, and the tests check that the two agree.

develop

uv sync
uv run pytest        # needs node for the Python / JS bender comparison
uv run ruff format src tests && uv run ruff check src tests
uv run flywire examples/chaser/chaser.kicad_pcb    # the demo, in build/

examples/chaser/chaser.kicad_pcb is written by examples/chaser/make_board.py from KiCad's stock footprints; it needs KiCad's pcbnew module, so run it with the Python KiCad installs (/usr/bin/python3 examples/chaser/make_board.py).

The page is src/flywire/web/ (index.html, style.css, bend.js, app.js), inlined into one file with the board data by report.html(); it uses no libraries.