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

# Pricing and billing

> How to work out a run's price, and how it is held and charged.

Spiral is pay as you go from one prepaid balance. There are no plans or minimums, and credits never expire.

## Before a run

Every tool has one pricing sentence: its base rate and unit in dollars, plus the input fields, minimums, rounding and
add-ons that change the calculation. It is `pricing_sentence` on [Inspect a model](/docs/api-reference/endpoint/inspect.md), with
your organization's fee, and the console's **Pricing** page lists them all.

```bash theme={null}
curl "https://api.spiral.ai/v1/tools/inspect?provider=fal&model=fal-ai/nano-banana-pro" \
  -H "Authorization: Bearer $SPIRAL_API_KEY"
```

```json theme={null}
{
  "pricing_sentence": "`resolution`: 1K (default) $0.195, 4K $0.39 per image. Billed on `num_images`, default 1."
}
```

Work a run's cost out from it: `duration` 10 at $0.07 per second is $0.70. The names in backticks are the run's own input
fields. A sentence that starts with "About" or "Up to", or says the final charge comes from usage, gives a typical cost or
a ceiling: the tool is priced by what it uses, which is only known after the run. `pricing_sentence` is null for a
tool that has no price yet.

## During and after a run

When a run starts, its estimate is **held** from your balance (`cost.state: held`). When it finishes, the hold is
replaced by the **charge** for the measured usage (`cost.state: settled`), and anything left is released.

A run that fails on Spiral's side or the provider's is not charged: the hold goes back to your balance.

## Limits

Give each agent its own key with a spend cap. The cap is reserved before a run starts, so it is never overshot. Add
credits, set auto top-up and balance alerts in the console under **Billing**.


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