Hi there!

Because the API uses a key, I'd like to ask if a request can be created so that, on application start (and, during runtime), you can ask whether your key is valid, and get back information about your current request quota (and any other pertinent information, such as possible downtime).

One of the side-benefits of this is that if, an API key is invalid, or the quota has been exhausted, the response will show that, and thus, not send any more requests (reducing possible load problems against the API).

http://api.stackoverflow.com/n.n/about/{key}

Returns

{
  "about": {
    "documentation": "Gets the status and quota of the account associated with 'key'.",
    "parameters": {
      "quota_used": {
        "description": "how many requests have been used against the current IP address",
        "values": "number"
      },
      "quota_remaining": {
        "description": "how many requests are available against the current IP address",
        "values": "number"
      },
      "server_time": {
        "description": "time on the server",
        "values": "number"
      },
      "next_downtime": {
        "description": "when (if any) the next expected downtime period will be",
        "values": "number"
      },
      "api_version": {
        "version": {
          "description": "api version",
          "values": "string"
        },
        "revision": {
          "description": "site revision",
          "values": "string"
        }
      }
    }
  }
}

I believe that X-RateLimit-Current and X-RateLimit-Max have been mentioned as a way of getting them from each response, and this is fine, I suppose.