---
title: Pricing models
description: What you can sell, and the declaration that states it.
---

Every pricing model is configuration. Pick the one that matches what you sell,
declare it in the catalog, and the deploy validates it.

| What you sell | Declare it with | Details |
| --- | --- | --- |
| A free tier | A plan with no `price` | [Plans](/concepts/plans#the-price) |
| A flat subscription | `price: { amount, currency, interval }` | [Plans](/concepts/plans#the-price) |
| An included allowance | `planItem(messages, { included: 100 })` | [Plans](/concepts/plans#what-a-plan-grants) |
| Paid overage | `overage: "bill"` and a `unitPrice` | [Plans](/concepts/plans#what-a-plan-grants) |
| Graduated or volume bands | `pricing: pricing({ kind, bands })` | [Plans](/concepts/plans#charge-bands) |
| Credits | `feature({ creditRates })` and `plan({ credits })` | [Credits](/concepts/credits) |
| Seats or other quantities | `kind: "non_consumable"` and `SetQuantity` | [Features](/concepts/features#pick-the-kind) |
| One-off credit packs | `kind: "one_off"` and `credits` | [Credits](/concepts/credits#expiry-and-one-off-packs) |
| Rollovers | `carryOver` on a plan item | [Plans](/concepts/plans#roll-over-what-the-month-did-not-spend) |
| Add-ons | `addOn: true` on a plan | [Plans](/concepts/plans#variants-add-ons-and-groups) |
| A trial | `trial: { days }` on a plan | [Plans](/concepts/plans#offer-a-trial) |
| Spend limits and usage alerts | `Customers.update({ billingControls })` | [Balances](/concepts/balances#set-a-spend-limit-and-an-alert) |
| Auto top-ups | `topUp` on a plan | [Credits](/concepts/credits#refill-before-the-pool-runs-out) |

Most catalogs combine a few of these. A typical product sells a free plan with
an allowance, a paid plan with more of it and a paid overage, and a one-off pack
for customers who run out.

## Charge bands

A plan item can price billable units with graduated or volume bands. Graduated
charges each band's rate for the units inside it. Volume charges every unit at
the rate of the band the total lands in.

```ts title="src/catalog.ts"
import { Paykit, pricing } from "@potion.run/paykit";

export const pro = Paykit.plan({
  id: "pro",
  price: { amount: 1_900, currency: "usd", interval: "month" },
  grants: [
    Paykit.planItem(messages, {
      included: 1_000,
      overage: "bill",
      pricing: pricing({
        kind: "graduated",
        currency: "usd",
        bands: [
          { upTo: 10_000, amount: 2, currency: "usd" },
          { upTo: "inf", amount: 1, currency: "usd" },
        ],
      }),
    }),
  ],
});
```

The last band must be `upTo: "inf"`. Each event records the difference the new
price makes, so the invoice is a sum of events and not a re-run of the formula
against the final count.

## What is not in the catalog

Some billing behavior belongs to the customer or the deployment, not to a plan.

- A customer's spend limit and usage alerts live on the customer, so support can
  change them without a deploy. See
  [Balances](/concepts/balances#set-a-spend-limit-and-an-alert).
- An enterprise contract that differs from every plan is a
  [custom plan](https://github.com/potion-run/paykit/blob/main/docs/BILLING-SURFACE.md),
  not a second pricing model.
- Tax, the card form and the invoice are the provider's. See
  [Providers](/providers).