Car audio fitment API — and a free vehicle dataset

Which wiring harness, dash kit, steering-wheel-control adapter, reverse camera or CarPlay retrofit module fits a given car? This repo is the open client and dataset for an API that answers that in one request.

• 483,653 vehicle-to-part fitment links
• 64,820 vehicles, model years 1995–2026, across 140 makes
• 20,874 parts in 11 categories
• Normalized from manufacturer application data — Metra, Connects2, PAC, Scosche, Crux, Aerpro, iDatalink, CARAV and others — into one vehicle taxonomy

Docs: https://ymmfit.com/fitment-api · OpenAPI: openapi.json · Coverage: https://ymmfit.com/fitment-api/coverage

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This is not a TecDoc alternative

TecDoc covers mechanical and service parts — brakes, filters, suspension. This covers 12V installation fitment: harnesses, fascias, SWC adapters, antenna adapters, cameras, CarPlay retrofits. Different data, no overlap, and no TecDoc licence is required to use any of it.

If you have ever tried to answer "will this head unit fit a 2013 Golf?" from a manufacturer PDF, this is the data you were looking for.

Try it without installing anything

# Everything that fits a 2013 VW Golf
curl "https://ymmfit.com/v1/parts?make=vw&model=golf&year=2013"

# Just the steering-wheel-control adapters
curl "https://ymmfit.com/v1/parts?make=vw&model=golf&year=2013&category=swc"

{
  "vehicle": { "year": 2013, "make": "VW", "model": "Golf" },
  "count": 23,
  "parts": [
    {
      "mpn": "CAVW02",
      "brand": "Aerpro",
      "category": "swc",
      "title": "Infodapter to suit Volkswagen",
      "note": "MK7",
      "source": "aerpro"
    }
  ]
}

That note is the qualifier — the condition the fitment depends on. A 2013 Golf spans two chassis generations and the adapter differs between them. Most fitment exports drop this field; it is the one that decides whether the part actually works.

The vehicle dataset is free, in full

data/vehicles.csv — 64,820 rows, every year/make/model in the catalog. data/makes.csv — 140 makes with counts and year ranges.

Free to use, including commercially — see data/LICENSE. Building a Year/Make/Model dropdown should not require a contract, and the vehicle list is not the hard part to compile — the part-to-vehicle links are.

The compilation is given away outright. What it deliberately does not do is claim rights over the underlying source catalogues, which belong to the manufacturers who published them — so no Creative Commons licence is applied and you are responsible for your own compliance. The terms say exactly that, in plain language.

The same data is live at /v1/makes and /v1/models, unmetered and without a key.

Make	slug	Models	Model-years	Years
Toyota	toyota	479	4,748	1995–2026
Mercedes	mercedes	589	4,625	1995–2026
BMW	bmw	503	4,481	1995–2026
Ford	ford	444	3,980	1995–2026
VW	vw	335	3,276	1995–2026
Lexus	lexus	304	2,578	1995–2026
Chevrolet	chevrolet	271	2,465	1995–2026
Audi	audi	223	2,388	1995–2026
Nissan	nissan	216	2,346	1995–2026
Hyundai	hyundai	162	1,752	1995–2026
Honda	honda	164	1,534	1995–2026
Dodge	dodge	111	1,447	1995–2026

→ all 140 makes

Install the client

npm install @rokasmen/car-audio-fitment

import { makes, models, parts, FitmentError } from "@rokasmen/car-audio-fitment";

const fits = await parts({ make: "vw", model: "golf", year: 2013, category: "harness" });
console.log(fits.count, "harnesses fit");

try {
  await parts({ make: "audi", model: "a4", year: 2018 });
} catch (e) {
  if (e instanceof FitmentError && e.code === "outside_sandbox") {
    // The make IS in the catalog — this is an access limit, not missing data.
    console.log(e.message);
  }
}

Zero dependencies. Node 18+ or any modern browser.

Runnable examples

File	What it does
examples/what-fits-my-car.mjs	Groups every part for one vehicle by category
examples/build-a-ymm-dropdown.html	A working YMM picker in one file, no build step
examples/load-the-dataset.py	Reads the CSV offline, no network

Endpoints

Endpoint	Returns	Key needed
GET /v1/meta	Catalog totals, categories, sources, sandbox coverage	No
GET /v1/makes	All 140 makes, with model counts and year ranges	No
GET /v1/models?make=	Every model under a make, with its years	No
GET /v1/parts?make=&model=&year=	Parts that fit one vehicle	Sandbox: no

Plain GET, JSON responses, CORS open. Base URL https://ymmfit.com/v1.

Access. The taxonomy is complete and free. Fitment is open for BMW, Chevrolet, Ford, Mercedes, Toyota, VW from model year 2012 onward (98,218 links). Anything beyond that needs a key — request one.

A make that exists in the catalog but sits outside the sandbox returns 403 outside_sandbox, never an empty list, so restricted access is never mistaken for missing data.

Part categories

Category	What it is	Parts
dashkit	Dash kit / fascia panel	7,480
carplay	CarPlay / Android Auto retrofit	6,894
speaker	Speaker adapter	2,633
harness	Wiring harness / ISO adapter	1,442
camera	Reverse camera interface	1,310
swc	Steering-wheel-control adapter	593
antenna	Antenna / DAB adapter	309
amp	Amplifier integration	134
aux	AUX / USB adapter	76
parking	Parking-sensor adapter	2
dab	DAB module	1

Where the data comes from

Every fitment link carries a source naming the manufacturer application guide it was normalized from.

Source	Fitment links
metra	114,956
connects2	89,677
carav	48,239
pac	41,540
carplay_stores	35,833
aerpro	26,084
metra_doc	23,258
housebrands	17,460
focal_inside	17,415
crux	16,249
idatalink	11,793
scosche_doc	10,067

Known limits, stated up front

• Coverage is deepest for mainstream European and North American models from roughly 2005 onward. Pre-2000 vehicles, commercial vans and low-volume models are thinner.
• There is no region parameter. Both EU and US vehicles are in the catalog — a Cadillac Escalade and a VW Golf sit side by side — but per-row market tagging is not yet reliable enough to filter on. Shipping the parameter would mean quietly returning the wrong set, so it is withheld until the tagging is fixed.
• Fitment is installation compatibility as published by the part manufacturer, not a guarantee for a specific factory-option combination. That is what note is for; where it is absent, the fitment is unconditional as published.
• Some model names still carry multi-model strings from their source guides (Silverado/gmc Sierra). Real data, imperfectly normalized.

Licence

Code — MIT (see LICENSE). The dataset in data/ is free to use commercially, with no rights asserted over the underlying source catalogues — see data/LICENSE.