# GPTZero API

> The AI integrity kit for your business.

[Quickstart](/quickstart/)Make your first API request.

[API reference](/api-reference/)Explore endpoints and try requests.

## Base URL

All endpoints are served from `https://api.gptzero.me`.

## Authentication

Send your API key in the `x-api-key` header. Requests with a missing or expired key get a `401`, and an unrecognized key gets a `403`. You can create a key on the [API page of the GPTZero app](https://app.gptzero.me/app/api).

To check that your key works, fetch your usage for the current billing cycle:

```sh
curl https://api.gptzero.me/v3/usage-stats \
  -H "x-api-key: $GPTZERO_API_KEY"
```