> For the complete documentation index, see [llms.txt](https://docs.posynt.win/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.posynt.win/getting-started/authentication.md).

# Authentication

Posynt uses **Bearer API keys**. Every request must include your key in the `Authorization` header.

```http
Authorization: Bearer psy_live_xxx
```

## Example

```bash
curl https://api.posynt.win/v1/tracks \
  -H "Authorization: Bearer psy_live_xxx"
```

## Best practices

* **Never** expose your key on the client side (browser, public mobile app). Call Posynt from your backend.
* Store the key in an environment variable, not hardcoded in your source.
* If a key leaks, **regenerate it** from the dashboard — the old one dies instantly.

## Two-factor authentication

You can enable **TOTP 2FA** in the dashboard settings (optional). When enabled, sensitive actions (regenerating your API key, deleting your account) require a 6-digit code from your authenticator app in addition to your API key.

## Authentication & limit errors

| Code                     | Meaning                                                                                                                                                 |
| ------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `401 Unauthorized`       | Missing, invalid or revoked key.                                                                                                                        |
| `402 Payment Required`   | Inactive or expired subscription.                                                                                                                       |
| `403 plan_limit_reached` | A `POST`/`PATCH` would exceed your plan's hashtag, account, engagement-tracking, or Discord webhook limit.                                              |
| `429 rate_limited`       | Over the per-minute request cap for your plan, or a sensitive endpoint's tighter limit — see [Rate limiting](/api-reference/overview.md#rate-limiting). |

Going over your **monthly alert quota** isn't an error at all: new posts just stop being stored/delivered until the period resets (see `GET /v1/usage`).

Error format:

```json
{
  "error": {
    "code": "unauthorized",
    "message": "Invalid API key."
  }
}
```


---

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