# Wenmar Open

> Free vehicle data for auto repair shops: VIN decoding and a year, make, model, submodel and engine catalog, built from NHTSA's vPIC. No API key and no account. Read-only. Data version 2026.09.

To decode a VIN, fetch `https://open.wenmarpro.com/v1/vin/` followed by the VIN, and read the JSON. No key, header or sign-up is needed. Spaces and dashes are ignored. A wrong check digit is not an error: the decode has `valid: false` and a warning, because many genuine VINs from outside North America fail the check. Up to 50 VINs at once: `POST https://open.wenmarpro.com/v1/vin/batch` with `{ "vins": [...] }`.

Responses are plain JSON with no wrapper. Errors are `{ "error": { "code", "message", "details" } }`. One address may make 600 requests a minute; over that the answer is 429 with `Retry-After`. Fields and endpoints are only ever added.

An MCP server is at `https://open.wenmarpro.com/mcp` (Streamable HTTP, no key). Its tools are `wenmar_vin` (actions `decode`, `batch`) and `wenmar_vehicles` (actions `years`, `makes`, `models`, `submodels`, `engines`, `search`, `entry`).

Vehicle ids such as `2019_honda_civic_si` are built from the year and the names, and stay the same between data releases for as long as the names do. Every reference page has a Markdown version at the same address with `.md` added. The data is what manufacturers reported to NHTSA. It can be incomplete, especially for vehicles never sold in the United States.

## API

- [OpenAPI description](https://open.wenmarpro.com/v1/openapi.json): every endpoint, parameter and response
- [Decode a VIN](https://open.wenmarpro.com/v1/vin/KM8K2CAB4PU001140): `GET /v1/vin/{vin}`, optional `?year=`
- [Years](https://open.wenmarpro.com/v1/vehicles/years): `GET /v1/vehicles/years`
- [Makes](https://open.wenmarpro.com/v1/vehicles/makes?year=2019): `GET /v1/vehicles/makes?year=`
- [Models](https://open.wenmarpro.com/v1/vehicles/models?make=honda&year=2019): `GET /v1/vehicles/models?make=&year=`
- [Submodels](https://open.wenmarpro.com/v1/vehicles/submodels?make=honda&model=civic&year=2019): `GET /v1/vehicles/submodels?make=&model=&year=`
- [Engines](https://open.wenmarpro.com/v1/vehicles/engines?make=honda&model=civic&year=2019): `GET /v1/vehicles/engines?make=&model=&year=&submodel=`
- [Search](https://open.wenmarpro.com/v1/vehicles/search?q=2019+civic+si): `GET /v1/vehicles/search?q=`
- [One vehicle by id](https://open.wenmarpro.com/v1/vehicles/2019_honda_civic): `GET /v1/vehicles/{id}`
- [Data version](https://open.wenmarpro.com/v1/meta): `GET /v1/meta`

## Docs

- [API reference](https://open.wenmarpro.com/docs.md): examples to copy, errors, limits and caching
- [Everything in one file](https://open.wenmarpro.com/llms-full.txt): the API reference, the VIN guides and the notes on the data, as one Markdown document
- [How to read a VIN, position by position](https://open.wenmarpro.com/guides/how-to-read-a-vin.md): What each of the 17 characters of a VIN means: the manufacturer, the vehicle, the check digit, the model year, the plant and the serial number.
- [Where to find the VIN on a vehicle](https://open.wenmarpro.com/guides/where-to-find-the-vin.md): The places a VIN is printed or stamped on a car, truck, motorcycle or trailer, where it is on the papers, and how to read it without mistakes.
- [What the first three characters of a VIN mean](https://open.wenmarpro.com/guides/wmi.md): The first three characters of a VIN are the World Manufacturer Identifier. What each one says, and how small manufacturers use six characters.
- [VIN model year chart: the 10th character](https://open.wenmarpro.com/guides/model-year.md): The tenth character of a VIN is the model year. A chart of every code from 1980 to 2039, and how the seventh character tells 1993 from 2023.
- [VIN check digit: how position 9 is worked out](https://open.wenmarpro.com/guides/check-digit.md): The ninth character of a VIN is a check digit worked out from the other sixteen. The weights, the letter values and a worked example.

## Reference pages

- [Makes](https://open.wenmarpro.com/makes.md): each make links to its models, and each model year to its trims and engines
- [One make, such as Honda](https://open.wenmarpro.com/makes/honda.md): `/makes/{make}.md`
- [One model year, such as the 2019 Honda Civic](https://open.wenmarpro.com/makes/honda/civic/2019.md): `/makes/{make}/{model}/{year}.md`
- [One manufacturer code, such as KM8](https://open.wenmarpro.com/wmi/KM8.md): `/wmi/{code}.md`

## Optional

- [About the data](https://open.wenmarpro.com/data.md): the data version, its source and how to download it
- [About](https://open.wenmarpro.com/about.md): who runs the service and what it keeps