Web & Mobile Team
8 years ago
Applications, Rate Limits & Throttling
We have had a steady stream of questions asking about how often, when, and from where developers can make requests to web services and APIs provided by Blizzard Entertainment. We'd like to spend some time describing the policy that will be in place for the newly released web APIs.

Developers are allowed to make around 3,000 requests per day to our API. The limit may seem low, but generally speaking, this number is good at representing how often a user could interact with our website both directly and indirectly.

That number isn't exactly 3,000 because we don't measure what developers do in terms of requests, but in cost of interaction. Internally, we give applications (both anonymous and registered) a credit value. Every request eats at that credit value. We do this because it lets us give different types of requests different cost values. Fetching the status of a realm, for example, costs much less than fetching information about a guild. We can even reward good behavior, such as using Last-Modified headers, by making requests cost less.

When an application doesn't have any credit left, it will start to become throttled. This simply means that the requests it makes will receive responses denying the data requested. The exact responses can be found in the API documentation.

As developers, you are responsible for not wasting credits or doing things that would otherwise get our attention. This can translate into a number of good practices that include keeping metrics on client library activity/usage, using queues to smooth out spikes in requests, etc.

If you operate a website or developed an application that eats past the 3,000 requests per day limit, we encourage you to read about and consider registering an application. Doing so allows you to make a large number of requests per day and ensures that your IP addresses can be accounted for when we update IP blacklists.
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