The rate limit for the Search API is 5 requests per second from a single IP address. There are no limits based on the total search volume or the number of requests coming from different IP addresses.
If you implement a “search-as-you-type” functionality, throttling with about 200ms delay between requests is recommended.
By default, rate limits are monitored over 15 minutes time period for the index-api.
Every API call that has limits returns rate limit information in the following headers:
Example headers returned by an API call: