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

# Authentication

Every call to the IDlayr API requires an OAuth2 access token. **All IDlayr API calls are backend-to-backend** — your server obtains and uses the token directly. The token never leaves your backend and is never given to a mobile app or any other untrusted client.

The mobile SDKs do **not** need an access token. They follow a pre-issued verification URL whose redirect chain is plain HTTP — see [Mobile SDKs](#mobile-sdks) below.

## OAuth2 client credentials grant

```bash
curl -X POST https://{data_residency}.api.idlayr.com/oauth2/token \
  -u "{client_id}:{client_secret}" \
  -d "grant_type=client_credentials" \
  -d "scope={product_scope}"
```

Notes:

* The token endpoint is **unversioned** in v1. The path is `/oauth2/token`, not `/oauth2/v1/token`.
* `{data_residency}` is `eu` or `us`. See [Data residency](/get-started/concepts/data-residency.md).
* `{product_scope}` depends on which product you're calling. See the product's prerequisites for the exact value (e.g. `secure_sna`, `sim_swap`, `reverse_sms`, `eligibility`).
* Authentication is HTTP Basic with `client_id` and `client_secret`.

Response:

```json
{
  "access_token": "...",
  "token_type": "bearer",
  "expires_in": 3600,
  "scope": "secure_sna"
}
```

## Using the access token

Include it as a Bearer token on every API request from your backend:

```
Authorization: Bearer {access_token}
```

Treat the token as a short-lived secret. Don't log it; don't expose it to untrusted clients; **don't ship it to mobile apps or browser code**.

## Token lifecycle

* Access tokens expire after `expires_in` seconds (typically one hour).
* Cache the token on your backend until it expires; request a fresh one before each expiry.
* There is no refresh-token grant for client credentials — re-request with the same flow.
* A token is scoped to one product. To call multiple products, request multiple tokens (one per scope).

## Revoking tokens

The unversioned `/oauth2/revoke` endpoint revokes a specific access token before its natural expiry. Use it if you suspect a token has leaked.

## Mobile SDKs

The iOS and Android SDKs **do not hold or use an OAuth2 access token**. Authentication of the verification round-trip stays on your backend:

1. Your **backend** mints an OAuth2 access token using the project credentials (above).
2. Your **backend** uses that token to create the verification check against the IDlayr API.
3. IDlayr returns a **verification `url`** along with the `check_id`. Your backend hands **only the URL** to your mobile app.
4. Your **mobile app** passes the URL to the SDK. The SDK follows the URL — the device-side step is a redirect chain that doesn't require an `Authorization` header.
5. Your **backend** learns the result via callback (recommended) or by polling.

For the per-product, per-platform code, see each product's iOS / Android integration page.

## Common errors

| HTTP | `error_code`      | Cause                                                             |
| ---- | ----------------- | ----------------------------------------------------------------- |
| 400  | `invalid_request` | Missing or malformed parameter (e.g. no `grant_type`)             |
| 401  | `invalid_client`  | `client_id` or `client_secret` incorrect                          |
| 401  | `unauthorized`    | Project not active, or credentials revoked                        |
| 400  | `invalid_scope`   | The requested scope is unknown or not authorised for this project |

See the API Reference Errors page for the full error taxonomy.

## Related

* [Credentials](/get-started/concepts/credentials.md) — where `client_id` and `client_secret` come from.
* [Project modes](/get-started/concepts/project-modes.md) — sandbox tokens come from the same endpoint but operate against simulated traffic.
* Cloudsmith entitlement tokens for SDK distribution (build-time, distinct from runtime API authentication) — see [SDKs](/get-started/sdks.md).


---

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