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

# Introduction

> Runtime financial guardrails for AI agents

Saturn is the execution layer for AI agents. It sits between your agent and the APIs it calls — handling auth, routing, budget enforcement, and per-call receipts.

<CardGroup cols={2}>
  <Card title="Quickstart" icon="rocket" href="/quickstart">
    Deploy your first agent in 5 minutes
  </Card>

  <Card title="Capabilities" icon="wand-magic-sparkles" href="/capabilities/overview">
    10 capability verbs for AI agents
  </Card>

  <Card title="SDK Reference" icon="code" href="/sdk/typescript">
    TypeScript SDK documentation
  </Card>

  <Card title="Pricing" icon="credit-card" href="/pricing">
    Pay-as-you-go with prepaid credits
  </Card>
</CardGroup>

## What Saturn Does

* **Routes requests** to 15+ upstream providers (OpenAI, Anthropic, Serper, E2B, and more)
* **Enforces budgets** with per-agent caps and daily limits
* **Processes payments** via card (USD) or Lightning (sats)
* **Logs everything** with full audit trail and cost attribution

## Runtime Enforcement vs Dashboards

Dashboards show you what happened. Saturn prevents what shouldn't happen.

| Approach           | When it acts         | Outcome                      |
| ------------------ | -------------------- | ---------------------------- |
| Dashboard alerts   | After spend occurs   | You see the bill             |
| Saturn enforcement | Before upstream call | Call rejected if over budget |

Saturn operates at the execution boundary. Every capability call passes through policy checks before reaching any upstream provider. Over-budget calls are rejected—not logged, not alerted, **rejected**.

## Architecture

```
┌─────────────────────────────────────────────────────────────┐
│                        Your Agent                           │
└─────────────────────────────┬───────────────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────┐
│                         Saturn                              │
│  ┌─────────────┐  ┌─────────────┐  ┌─────────────────────┐  │
│  │   Policy    │  │   Ledger    │  │   Provider Router   │  │
│  │   Engine    │──│   (Credits) │──│   (OpenAI, etc.)    │  │
│  └─────────────┘  └─────────────┘  └─────────────────────┘  │
└─────────────────────────────┬───────────────────────────────┘
                              │
                              ▼
┌─────────────────────────────────────────────────────────────┐
│              Upstream Providers (OpenAI, Anthropic, etc.)   │
└─────────────────────────────────────────────────────────────┘
```

Every call:

1. Authenticated via agent API key
2. Checked against policy (caps, allowed capabilities)
3. Quoted against current credit balance
4. Executed only if all checks pass
5. Settled atomically with receipt issued

## When to Use Saturn

<CardGroup cols={2}>
  <Card title="Autonomous Agents" icon="robot">
    AI agents that call paid APIs without human oversight
  </Card>

  <Card title="Multi-tenant SaaS" icon="users">
    Per-user AI features with isolated budgets
  </Card>

  <Card title="Production Systems" icon="shield-check">
    Where cost overruns are unacceptable
  </Card>

  <Card title="Multi-Provider" icon="layer-group">
    Unified budgets across OpenAI, Anthropic, and more
  </Card>
</CardGroup>

## When Not to Use Saturn

* Single-user CLI tools with manual oversight
* Development environments where cost is irrelevant
* Systems where you want unbounded spend
* Scenarios requiring direct provider API access for unsupported features