A harness job is mostly catalog parts — connectors, terminals, contacts, backshells, sleeving — plus wire, and wire is where most inventory tools give up: it is bought on spools, stocked in meters, and consumed in millimeter lengths. PartsBox keeps all three correct.
Give wire a unit of measure, and stock, pricing, purchasing, and builds all run in that unit. A spool of 10 meters has a package quantity of 10000 mm: order three spools and PartsBox records the order in spools and the stock in millimeters, with the price shown per spool and per unit, such as $0.14/mm. Stock is fractional — 2.5 m left on a spool is 2.5 m — and a build that needs 1.5 m deducts exactly 1.5 m. The same works by weight and by volume, for solder, sleeving sold by the meter, or potting compound.
Each assembly or harness variant is a project: the connectors, terminals, contacts, wire lengths, and non-part lines such as labor or testing. Price it from live distributor offers, with price breaks and order multiples handled per offer, and import the parts list from a CSV your design tool exports. Because connectors and terminals are shared across jobs, a purchase list combines every job you have open, subtracts stock, and orders the shortfall once — instead of once per job.
Automotive, aerospace, and medical harness work has to show where materials came from. With lot control, each reel of terminals and each spool of wire is a distinct lot with its own source and cost. A length cut from a spool keeps its link to the original, and every build records the exact lots it consumed, so from a supplier's lot number you trace forward to the assemblies that used it, and from a delivered assembly back to its material sources — with certificates of conformance attached to the lots they cover.
PartsBox manages the parts, stock, BOMs, purchasing, and lots for harness work. It is not a harness-engineering tool: cut lists, crimp specifications, formboard drawings, and test procedures live in your design and production tools. PartsBox is the inventory and material-traceability layer under them.
Inventory, units of measure, and builds are in every plan, including the free Maker plan. Purchasing and BOM pricing start on the Essentials plan; lot traceability is on the Control plan.