> ## Documentation Index
> Fetch the complete documentation index at: https://docs.aflux.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Balance and transactions

> Prepaid credit, bonus credit, and the ledger behind both.

Aflux runs on a prepaid balance. Campaigns draw from it; you top it up by [deposit](/billing/deposits) or [promo code](/billing/promo-codes).

## Reading the balance

```bash theme={null}
curl "$AFLUX_API/billing/balance" -H "Authorization: Bearer $AFLUX_KEY"
```

```json theme={null}
{ "currency": "USD", "available": "1240.00", "bonus": "50.00", "bonusSpentFirst": true }
```

| Field             | Meaning                                                |
| ----------------- | ------------------------------------------------------ |
| `available`       | Credit you paid for.                                   |
| `bonus`           | Credit from promo codes.                               |
| `bonusSpentFirst` | Whether bonus credit is drawn down before paid credit. |

## The ledger

```bash theme={null}
curl "$AFLUX_API/billing/transactions" -H "Authorization: Bearer $AFLUX_KEY"
```

Every entry carries the amount, the balance after it, and what caused it:

| `type`            | Cause                                                    |
| ----------------- | -------------------------------------------------------- |
| `DEPOSIT`         | A completed crypto payment.                              |
| `CAMPAIGN_CHARGE` | A campaign committing its budget.                        |
| `REFUND`          | Money returned — a released commitment, a failed payout. |
| `PROMO_BONUS`     | A redeemed promo code.                                   |

`referenceType` (`PAYMENT`, `CAMPAIGN`, `PROMO`, `MANUAL`) plus `referenceId` point at what the entry is about, and `referenceName` and `projectName` are there so a statement reads without extra lookups.

The response pages with `nextCursor`.

<Note>
  A campaign takes its **whole budget** out of the balance at creation. Money released later — a cancelled placement, a failed payout — comes back as a `REFUND` entry rather than by reversing the original charge.
</Note>