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

# Introduction

> What is Nozle and who is it for

Nozle is billing infrastructure for AI products. It combines usage metering, subscriptions, product credits, entitlements, payments, and unit-economics reporting behind one API and SDK surface.

## Who is Nozle for?

Nozle is built for AI companies that:

* Bill customers based on API calls, tokens, compute time, or other usage metrics
* Need visibility into per-customer and per-model costs
* Want feature gating and usage limits without building entitlement logic from scratch
* Use Stripe for payments and need managed checkout flows

## Key capabilities

| Capability              | What it does                                                                              |
| ----------------------- | ----------------------------------------------------------------------------------------- |
| **Usage-based billing** | Meter product events, aggregate usage, and invoice on your configured billing schedule    |
| **Entitlements**        | Evaluate feature access and usage limits from a trusted backend                           |
| **Product credits**     | Grant, sell, allocate, and atomically consume exact-decimal product units                 |
| **Margin intelligence** | Per-customer, per-model cost tracking so you know your true margins                       |
| **Stripe checkout**     | Payment-aware checkout and subscription transitions with webhook-authoritative activation |

## Architecture

Nozle is built around two layers:

1. **Nozle API** -- The backend for checkout, subscriptions, credits, entitlements, margin analytics, and usage ingestion. Runs at `api.nozle.app`.

2. **SDKs** -- Client and server libraries that connect your application to Nozle.

<Info>
  You interact with Nozle through the SDKs or REST API -- all the complexity of billing, entitlements, and margin lives behind a single API surface.
</Info>

## SDKs

Nozle ships three SDKs:

* **`@nozle-js/react`** -- Public catalog, checkout orchestration, pricing, usage, and presentational gate components.
* **`@nozle-js/node`** -- Server-side billing, credits, subscriptions, event tracking, entitlements, and margin queries.
* **`nozle-sdk`** (Python) -- Typed server-side access to the same core billing and credit workflows.

## Production URLs

| Service   | URL                                      |
| --------- | ---------------------------------------- |
| Dashboard | [app.nozle.app](https://app.nozle.app)   |
| API       | [api.nozle.app](https://api.nozle.app)   |
| Docs      | [docs.nozle.app](https://docs.nozle.app) |

## Next steps

Head to the [Quickstart](/guides/getting-started/quickstart) to track your first event and connect checkout, or read [Architecture](/guides/getting-started/architecture) for a deeper look at the trust boundaries and data flow.