The error code 429 is returned when your app has sent too many requests in a given amount of time. This is called rate limiting and protects the API and the backend system from being called too often.

According to the Appylar documentation of their REST API, the default rate limit is 60 seconds. Let's say that your app fetches new ads at a given point in time. After 45 seconds, it tries to fetch new ads again. In that case, the rate limit would kick in and force the SDK to wait another 15 seconds before automatically sending the request again.

Normally, this is not a problem since there are 10 banners and 10 interstitials in the buffer. Those should definitely last longer than 60 seconds in your app. However, if you manually show/hide ads for testing purposes, you may end up triggering the rate limit.

In sum, rate limiting is normally nothing you have to worry about. Even so, when it occurs, the SDK will handle it automatically by waiting the specified time before retrying.