# Buy a credit pack on the saved card

`POST /v1/billing/purchase`

Buys a credit pack on the account's saved card, from **$50** for 500 credits, only if the account owner has turned agent purchases on.

- **Auth:** API key ([Authentication](https://installgraph.com/docs/authentication.md))
- **Scope:** none
- **Cost:** Charges the account's saved card the pack price ($50 to $1,000).

Use it when a job runs out of credits (`402 insufficient_credits`) and the owner has allowed it. Otherwise hand `error.offers.pack.buyUrl` to a person.

Buys `starter` ($50, 500 credits), `growth` ($150, 2,500), `pro` ($400, 10,000) or `scale` ($1,000,
40,000) on the card saved at the account's first checkout. Off until the account owner turns on
agent purchases and sets per-purchase and 30-day limits (`403 purchase_not_allowed`).

## Request

```bash
curl -X POST "https://api.installgraph.com/v1/billing/purchase" \
  -H "Authorization: Bearer $INSTALLGRAPH_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"pack":"starter"}'
```

### Body

JSON.

| Field | Type | Description |
| --- | --- | --- |
| `pack` | string | One of `starter`, `growth`, `pro`, `scale`. |

## Response

`200`. The example's stores are fictional.

```json
{
  "data": {
    "pack": "starter",
    "credits": 500,
    "priceUsd": 50,
    "balance": 546
  }
}
```

Every keyed response also carries `meta` (`requestId`, `creditsUsed`, `creditsRemaining`, `freeRepulls`) and the `X-Credits-*` and `X-RateLimit-*` headers. See [Credits](https://installgraph.com/docs/credits.md) and [Rate limits](https://installgraph.com/docs/rate-limits.md).

## Errors

| Status | Code | Meaning | What to do |
| --- | --- | --- | --- |
| 402 | `spend_cap_reached` | Purchases would pass $1,000 in 30 days. | Talk to us for more: `error.offers.talkToUs.url`. |
| 402 | `payment_failed` | The saved card was declined. | Ask the account owner to update the card at installgraph.com/account. |
| 403 | `purchase_not_allowed` | Agent purchases are off for this account, the pack is over the owner's limits, or the key has no account. | Hand `error.offers.pack.buyUrl` to a person; the owner sets limits at `error.settings`. |
| 409 | `no_payment_method` | No card is saved, so nothing can be bought off-session. | Buy a pack once at installgraph.com/account to save a card. |

All codes: [Errors](https://installgraph.com/docs/errors.md).