---
title: "Authentication"
description: "Authenticate API requests safely with the X-Api-Key header."
---

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

# Authentication

Send your API key in the `X-Api-Key` header on every authenticated request.

```http
X-Api-Key: your-api-key
```

```bash
curl https://api.uncaptcha.io/v1/balance/get \
  --header "X-Api-Key: $UNCAPTCHA_API_KEY"
```

## Authentication errors

```json
{
  "success": false,
  "message": "X-Api-Key header is missing"
}
```

An absent, invalid, disabled, expired, or unauthorized key is rejected before a
solve starts and is not charged.

Source: https://docs.uncaptcha.io/getting-started/authentication/index.mdx