Based on the API provided by the Washington State Department of Revenue, WA Sales Tax Lookup, implements an identical API that responds in plain text or XML and a modern version that responds in JSON.

WA Sale Tax Lookup is architected as a standalone application or microservice so that you're not dependent on the State of Washington's IT infrastructure. Once this app has cached the sale tax data from the state's website, which happens on start up, you're good to go until the next quarter. When the state updates the sale tax rates the app will automatically ingest the new data.

Built for high reliability and performance WA Sales Tax Lookup is a .NET 5 Web API project backed with an SQLite database that implements the OpenAPI standard and offers friendly Swagger UI documentation to make integrating with it a breeze. 🚀