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

# Introduction

> Overview of Cello API for referral codes, authentication, and quickstart.

## Cello API

The Cello API provides endpoints to:

* Validate referral codes (`ucc`)
* Retrieve active referral links
* Send referral events for signups and purchases

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## Base URLs

Use the URL that matches your environment:

| Environment | Base URL                        |
| ----------- | ------------------------------- |
| Sandbox     | `https://api.sandbox.cello.so/` |
| Production  | `https://api.cello.so/`         |

***

## Authentication

Authenticate API requests using an `accessToken` in the Authorization header.

Obtain your `accessKeyId` and `secretAccessKey` from the [Access Keys](https://portal.cello.so/integrations/accesskeys) page in your dashboard.