Rates and tax you control, with a safety net.

Your own rules, versioned

Shipping and tax configuration is a versioned document: edit a draft, publish it, and exactly one version is live per environment. Old versions are kept, so you can always explain how a past order was quoted.

Built-in shipping covers most stores without a third party:

• Zones by country, state, and postal code — exact, prefix, or range — with priorities when they overlap.
• Methods for shipping or pickup, with a base rate and handling fee.
• Conditions on subtotal, weight, and item count, plus date windows and delivery estimates.

Tax regions, rules, and categories work the same way.

Or connect a provider

• Live carrier rates from Shippo or EasyPost at cart and checkout.
• Tax from Avalara AvaTax — calculated in real time, and filed, refunded, and voided as the order changes, with exemption certificates, address validation, and customs duty.

Every provider call is logged with what was sent and what came back.

A safety net for every provider

Providers fail. Throttle decides in advance what happens when one does:

• Shipping is lenient by default. If a carrier doesn’t answer within five seconds, checkout falls back to your own rates and flags it, so an outage never blocks a sale.
• Tax is strict by default. If the tax engine can’t be reached at final checkout, Throttle stops before charging rather than collect the wrong tax. Cart estimates keep working.

Five failures in a row mark a connection unhealthy and alert your admins.

Quotes from the browser

Shipping and tax quotes can be requested with a publishable key, straight from your storefront, without exposing anything that reads your data.

Good to know

• Saving shipping and tax in the dashboard publishes it straight away; there’s no staged rollout.
• Exchanges are not re-quoted for tax.
• Labels and fulfillment live in your shipping tool — ShipStation syncs tracking back.