Use Avalara's REST API to calculate tax in real time. Build a custom integration, or extend an existing connector.
SDKs for many popular programming languages makes it easy to get your project started.
A full API reference with code samples, a "quick start" developer guide, an active developer community and free developer office hours for Q&A are just a few ways we support our API developers.
Our API is backed by our best in class tax research, and gives you the right tax rate for each transaction. If you're just looking tax rates by zip code, we offer a free tax rates API.