Avalara

About

Tax calculation API (AvaTax) for sales and use tax, VAT and other transaction taxes, with address-based jurisdiction lookup and rates for 200+ countries. Aimed at businesses selling into many US states; plans are priced per state after a 90-day developer trial.

What you can do with it

• Calculate sales tax for a cart, order or invoice at checkout
• Record committed transactions that feed tax returns and filing
• Validate addresses and map them to the correct tax jurisdictions

Get started

1. Start the 90-day AvaTax developer trial
2. Get your account ID and license key for the sandbox

Example

curl -X POST https://sandbox-rest.avatax.com/api/v2/transactions/create \
  -u "$AVALARA_ACCOUNT_ID:$AVALARA_LICENSE_KEY" \
  -H "Content-Type: application/json" \
  -d '{"type": "SalesInvoice", "companyCode": "DEFAULT", "date": "2026-09-25", "customerCode": "ABC",
    "addresses": {"singleLocation": {"line1": "2000 Main Street", "city": "Irvine", "region": "CA", "country": "US", "postalCode": "92614"}},
    "lines": [{"number": "1", "quantity": 1, "amount": 100, "taxCode": "PS081282", "description": "Yarn"}]}'

Details

Hosting

Hosted service

Available in

Worldwide

Official SDKs

C#, Java, JavaScript/TypeScript, Python, PHP, Ruby

MCP server

Remote