Rate limiting guidelines
At PayPal, our primary focus in supporting you is site availability and security. While we do not publish a specific rate limiting policy, the decision to rate limit is based on traffic patterns. If we identify traffic that appears to be abusive, we may temporarily rate limit until we are confident that the activity is not going to be problematic for PayPal, merchants, or customers.
We are constantly evaluating traffic as it surges and subsides; therefore we adjust our policies to ensure maximum protection for the site. If you or your customers are receiving an HTTP 429 status code (too many requests), we may have identified anomalous traffic and started rate limiting in order to ensure site stability. If this has or will negatively affect your integration, please contact Merchant Technical Support for assistance.