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

# Authentication

> Configure your Paubox API credentials for the Go SDK.

## Obtain your credentials

The Email API client requires two credentials:

* **API key**: a secret token that authenticates your requests
* **Username**: your Paubox API endpoint username (not your login email)

Both are available in the [Paubox dashboard](https://next.paubox.com) under **API Credentials**.

## Create a client

Pass the API key and username directly to `paubox.New`:

```go theme={null}
import (
    "os"
    paubox "github.com/paubox/paubox-go"
)

client, err := paubox.New(
    os.Getenv("PAUBOX_API_KEY"),
    os.Getenv("PAUBOX_USERNAME"),
)
if err != nil {
    log.Fatal(err)
}
```

The SDK sets the `Authorization` header automatically on every request:

```
Authorization: Token token=YOUR_API_KEY
```

## Environment variables

The SDK does not read environment variables automatically — you must read them and pass the values to `paubox.New`. The convention used throughout this documentation is `PAUBOX_API_KEY` and `PAUBOX_USERNAME`.

## Forms client

The Forms client (`paubox.NewFormsClient`) requires no credentials. Form submissions are associated with the form ID, not an API key.

```go theme={null}
fc, err := paubox.NewFormsClient()
if err != nil {
    log.Fatal(err)
}
```

## Security notes

* Never hard-code credentials in source files.
* The SDK never logs request bodies, response bodies, or the `Authorization` header.
* Clients are safe to create once and reuse across goroutines for the lifetime of your application.