No code or server needed: put the waypoints in the link.
Coordinates are in-game zone coordinates, the numbers /way and coordinate add-ons show: 0–100 across and down the zone map (top-left 0,0), with the zone named by its UiMap ID. Durotar 1411, Mulgore 1412, The Barrens 1413, Tirisfal Glades 1420, Silverpine Forest 1421, Orgrimmar 1454, Thunder Bluff 1456, Undercity 1458. The Maps tab lists every ID.
Link format, letters, digits and hyphens only:
<page>#r-<uiMapID>[type]-<x×100>-<y×100>[-Label-Words]-<next waypoint>…
[type] is one optional letter after the map ID: q quest pickup, t turn-in, g go to (default), k kill/collect, i interact/use, f flight/boat, h hearth, n note. See AGENTS.md for the full guide.
x×100 and y×100 are whole numbers (61.20 → 6120). Words after a waypoint's three numbers are its label; a label word must contain a letter, and punctuation is dropped.
Example, Undercity flight master → Brill → The Sepulcher:
https://claude.ai/artifact/A9r25xHiAAg6DoByotmtVZ#r-1458f-6310-4830-Undercity-1420q-6097-5270-Brill-1421-4560-4240-The-Sepulcher
The Import box also takes TomTom lines (/way #1420 61.0 52.0 Brill or /way Tirisfal Glades 61 52 Brill), JSON ([{"uiMapID":1420,"x":61,"y":52,"label":"Brill"}]) and the readable form r=1420:61,52:Brill;1421:45.56,42.42.
Legs on one continent follow walkable terrain when that data is loaded; legs between continents (boats, zeppelins, flights) are not drawn.