Our Methodology

1. Direct Database Integration

AssemblyCheck does not rely on static tables or speculative manufacturing charts. When you enter a VIN, our tool queries the vPIC (Product Information Catalog) API, maintained directly by the National Highway Traffic Safety Administration (NHTSA), an agency of the U.S. Department of Transportation.

We retrieve raw manufacturer specifications registered under federal vehicle classification protocols, including the specific final assembly plant address, make, model, year, vehicle type, and gross vehicle weight rating (GVWR).

2. The Final Assembly Standard

Our database engine differentiates itself by verifying the exact Plant Country, rather than checking the first character of the VIN (known as the World Manufacturer Identifier or WMI).

Checking only the first character is an unreliable heuristic. Because automakers frequently manufacture identical models across multiple countries, unit-level assembly details must be decoded. For example, a Chevrolet Silverado or Honda Civic may be assembled in either the USA or in imported facilities depending on the exact trim, factory capacity, or batch.

3. Caching & Privacy Protocols

• 90-Day Caching: Once a VIN is decoded successfully, the decoded data is cached on our secure Cloudflare KV nodes for up to 90 days. Because manufacturing assembly plant locations do not change post-hoc, caching ensures Core Web Vitals are optimized and limits unnecessary API load.
• No PII Storage: A vehicle's VIN identifies the chassis, but does not identify the owner. AssemblyCheck does not collect, request, or store any Personally Identifiable Information (PII) such as name, email, street address, or driver's licenses.
• Local Computations: Financial parameters (such as loan interest rates, principal size, and Modified Adjusted Gross Income) are computed locally inside your browser using client-side JavaScript. This private financial data is never sent to or cached on our servers.