Pricing

The tax-compute API that's correct by construction. Usage-based, billed per compute call. Perpetual free tier — no credit card to start.

Free

$0/mo

Evaluate forever — no card.

$29/mo

For a production integration.

$99/mo

Growing usage + analytics.

$399/mo

High volume + priority support.

Volume pricing, SLA, BAA, and dedicated support.

One billable call = one compute request. An HTTP 200is billable whether the engine computed a result or honestly declined — you pay for the answer, including a clean “this case is out of scope.”
Errors are free. 4xx (bad request) and 5xx (server / metering) responses are never billed.
Retries bill once. Send an Idempotency-Key and a retry replays the first response, billed exactly once — no double-charge on a network hiccup.
Your monthly limit is a hard cap — no surprise overage. At the limit, calls return429 until the next cycle or an upgrade. The limit is shared across all of your API keys.
Per-minute rate limits protect the service; exceeding one returns 429(retry in a moment), never a charge.

See the API docs for the full request/response contract and error semantics.