Rate Limiting
From HNS.dev
The HNS.dev API only allows clients to make a limited number of calls in a given period. The default rate limit for calls to the HNS.dev API is 150 requests per hour. The API does account-based rate limiting. Your application should recognize it is being rate-limited by the REST API if it receives begins to receive 'Too many hits' errors.
Whitelisting
Some applications find that the default limit proves insufficient. Under such circumstances, we offer whitelisting. Each whitelisted entity is allowed a higher number of requests per hour, based on need. If you are developing an application that should be considered for whitelisting, please contact the administrators. Our manual review process can take up to a week. Approval or rejection for whitelisting requests is emailed to the email address associated with the account that filed the application.

