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

# Vayu API

> Full API reference for the Vayu billing platform

## Overview

The Vayu API gives you programmatic access to your billing operations — create and manage customers, contracts, catalog products, events, invoices, credits, measurements, and webhooks. All resources are accessible via RESTful HTTP endpoints and are supported by official SDKs in TypeScript, Python, and Go.

**Base URL:** `https://connect.withvayu.com`

**OpenAPI Spec:** [Download vy-openapi.yml](https://raw.githubusercontent.com/vayucode/docs/main/config/vy-openapi.yml)

<CardGroup cols="3">
  <Card title="Authentication" icon="key" href="/api-reference/pages/connecting-to-vayu">
    Get your credentials and make your first authenticated request
  </Card>

  <Card title="SDKs" icon="cube" href="/api-reference/pages/sdk">
    Official client libraries for TypeScript, Python, and Go
  </Card>

  <Card title="Webhooks" icon="bell" href="/api-reference/pages/webhooks">
    Receive real-time event notifications
  </Card>
</CardGroup>

## Key concepts

* **Pagination** — All list endpoints use cursor-based pagination. See [Pagination](/api-reference/pages/pagination).
* **Idempotency** — Events support an idempotency key via the `ref` field. See [Idempotency](/api-reference/pages/idempotency).
* **Batch ingestion** — Send 1–1,000 events per request (256 KB max). See [Sending Events](/api-reference/pages/sending-events).
* **Error handling** — All errors return structured JSON with a machine-readable code. See [Errors](/api-reference/pages/errors).
* **Rate limits** — See [Rate Limits](/api-reference/pages/rate-limits).